CVE-2021-46981

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2021-46981", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-02-27T18:42:55.945Z", "datePublished": "2024-02-28T08:13:10.972Z", "dateUpdated": "2026-05-23T15:18:51.744Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-23T15:18:51.744Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: Fix NULL pointer in flush_workqueue\n\nOpen /dev/nbdX first, the config_refs will be 1 and\nthe pointers in nbd_device are still null. Disconnect\n/dev/nbdX, then reference a null recv_workq. The\nprotection by config_refs in nbd_genl_disconnect is useless.\n\n[ 656.366194] BUG: kernel NULL pointer dereference, address: 0000000000000020\n[ 656.368943] #PF: supervisor write access in kernel mode\n[ 656.369844] #PF: error_code(0x0002) - not-present page\n[ 656.370717] PGD 10cc87067 P4D 10cc87067 PUD 1074b4067 PMD 0\n[ 656.371693] Oops: 0002 [#1] SMP\n[ 656.372242] CPU: 5 PID: 7977 Comm: nbd-client Not tainted 5.11.0-rc5-00040-g76c057c84d28 #1\n[ 656.373661] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014\n[ 656.375904] RIP: 0010:mutex_lock+0x29/0x60\n[ 656.376627] Code: 00 0f 1f 44 00 00 55 48 89 fd 48 83 05 6f d7 fe 08 01 e8 7a c3 ff ff 48 83 05 6a d7 fe 08 01 31 c0 65 48 8b 14 25 00 6d 01 00 <f0> 48 0f b1 55 d\n[ 656.378934] RSP: 0018:ffffc900005eb9b0 EFLAGS: 00010246\n[ 656.379350] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000\n[ 656.379915] RDX: ffff888104cf2600 RSI: ffffffffaae8f452 RDI: 0000000000000020\n[ 656.380473] RBP: 0000000000000020 R08: 0000000000000000 R09: ffff88813bd6b318\n[ 656.381039] R10: 00000000000000c7 R11: fefefefefefefeff R12: ffff888102710b40\n[ 656.381599] R13: ffffc900005eb9e0 R14: ffffffffb2930680 R15: ffff88810770ef00\n[ 656.382166] FS: 00007fdf117ebb40(0000) GS:ffff88813bd40000(0000) knlGS:0000000000000000\n[ 656.382806] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 656.383261] CR2: 0000000000000020 CR3: 0000000100c84000 CR4: 00000000000006e0\n[ 656.383819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n[ 656.384370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n[ 656.384927] Call Trace:\n[ 656.385111] flush_workqueue+0x92/0x6c0\n[ 656.385395] nbd_disconnect_and_put+0x81/0xd0\n[ 656.385716] nbd_genl_disconnect+0x125/0x2a0\n[ 656.386034] genl_family_rcv_msg_doit.isra.0+0x102/0x1b0\n[ 656.386422] genl_rcv_msg+0xfc/0x2b0\n[ 656.386685] ? nbd_ioctl+0x490/0x490\n[ 656.386954] ? genl_family_rcv_msg_doit.isra.0+0x1b0/0x1b0\n[ 656.387354] netlink_rcv_skb+0x62/0x180\n[ 656.387638] genl_rcv+0x34/0x60\n[ 656.387874] netlink_unicast+0x26d/0x590\n[ 656.388162] netlink_sendmsg+0x398/0x6c0\n[ 656.388451] ? netlink_rcv_skb+0x180/0x180\n[ 656.388750] ____sys_sendmsg+0x1da/0x320\n[ 656.389038] ? ____sys_recvmsg+0x130/0x220\n[ 656.389334] ___sys_sendmsg+0x8e/0xf0\n[ 656.389605] ? ___sys_recvmsg+0xa2/0xf0\n[ 656.389889] ? handle_mm_fault+0x1671/0x21d0\n[ 656.390201] __sys_sendmsg+0x6d/0xe0\n[ 656.390464] __x64_sys_sendmsg+0x23/0x30\n[ 656.390751] do_syscall_64+0x45/0x70\n[ 656.391017] entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\nTo fix it, just add if (nbd->recv_workq) to nbd_disconnect_and_put()."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/block/nbd.c"], "versions": [{"version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "1c4962df938891af9ab4775f5224ef8601764107", "status": "affected", "versionType": "git"}, {"version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "cde4b55cfb24522dcbba80bbdb0c082303e76c43", "status": "affected", "versionType": "git"}, {"version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "b31d237796fd618379ec8e0f4de3370b5e4aeee7", "status": "affected", "versionType": "git"}, {"version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc", "status": "affected", "versionType": "git"}, {"version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "79ebe9110fa458d58f1fceb078e2068d7ad37390", "status": "affected", "versionType": "git"}, {"version": "0b584bf573ae59021069c056c22d65d5721910cb", "status": "affected", "versionType": "git"}, {"version": "9f0f39c92e4f50189155dfb13bb5524372e40eba", "status": "affected", "versionType": "git"}, {"version": "92ec11cccb7fc14331e000ab2337f60aa433433e", "status": "affected", "versionType": "git"}, {"version": "4.14.149", "lessThan": "4.15", "status": "affected", "versionType": "semver"}, {"version": "4.19.79", "lessThan": "4.20", "status": "affected", "versionType": "semver"}, {"version": "5.3.6", "lessThan": "5.4", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["drivers/block/nbd.c"], "versions": [{"version": "5.4", "status": "affected"}, {"version": "0", "lessThan": "5.4", "status": "unaffected", "versionType": "semver"}, {"version": "5.4.120", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.38", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.11.22", "lessThanOrEqual": "5.11.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.12.5", "lessThanOrEqual": "5.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.13", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "5.4.120"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "5.10.38"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "5.11.22"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "5.12.5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4", "versionEndExcluding": "5.13"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14.149"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19.79"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.3.6"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/1c4962df938891af9ab4775f5224ef8601764107"}, {"url": "https://git.kernel.org/stable/c/cde4b55cfb24522dcbba80bbdb0c082303e76c43"}, {"url": "https://git.kernel.org/stable/c/b31d237796fd618379ec8e0f4de3370b5e4aeee7"}, {"url": "https://git.kernel.org/stable/c/54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc"}, {"url": "https://git.kernel.org/stable/c/79ebe9110fa458d58f1fceb078e2068d7ad37390"}], "title": "nbd: Fix NULL pointer in flush_workqueue", "x_generator": {"engine": "bippy-1.2.0"}}, "adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2021-46981", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2024-02-28T19:55:25.767523Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-06-04T17:13:11.297Z"}}, {"providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:24:38.514Z"}, "title": "CVE Program Container", "references": [{"url": "https://git.kernel.org/stable/c/1c4962df938891af9ab4775f5224ef8601764107", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/cde4b55cfb24522dcbba80bbdb0c082303e76c43", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/b31d237796fd618379ec8e0f4de3370b5e4aeee7", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/79ebe9110fa458d58f1fceb078e2068d7ad37390", "tags": ["x_transferred"]}]}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CVE Program Container", "references": [{"url": "https://git.kernel.org/stable/c/1c4962df938891af9ab4775f5224ef8601764107", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/cde4b55cfb24522dcbba80bbdb0c082303e76c43", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/b31d237796fd618379ec8e0f4de3370b5e4aeee7", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/79ebe9110fa458d58f1fceb078e2068d7ad37390", "tags": ["x_transferred"]}], "providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:24:38.514Z"}}, {"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2021-46981", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2024-02-28T19:55:25.767523Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-05-23T19:01:13.707Z"}, "title": "CISA ADP Vulnrichment"}], "cna": {"title": "nbd: Fix NULL pointer in flush_workqueue", "affected": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "1c4962df938891af9ab4775f5224ef8601764107", "versionType": "git"}, {"status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "cde4b55cfb24522dcbba80bbdb0c082303e76c43", "versionType": "git"}, {"status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "b31d237796fd618379ec8e0f4de3370b5e4aeee7", "versionType": "git"}, {"status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc", "versionType": "git"}, {"status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "lessThan": "79ebe9110fa458d58f1fceb078e2068d7ad37390", "versionType": "git"}, {"status": "affected", "version": "0b584bf573ae59021069c056c22d65d5721910cb", "versionType": "git"}, {"status": "affected", "version": "9f0f39c92e4f50189155dfb13bb5524372e40eba", "versionType": "git"}, {"status": "affected", "version": "92ec11cccb7fc14331e000ab2337f60aa433433e", "versionType": "git"}, {"status": "affected", "version": "4.14.149", "lessThan": "4.15", "versionType": "semver"}, {"status": "affected", "version": "4.19.79", "lessThan": "4.20", "versionType": "semver"}, {"status": "affected", "version": "5.3.6", "lessThan": "5.4", "versionType": "semver"}], "programFiles": ["drivers/block/nbd.c"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "5.4"}, {"status": "unaffected", "version": "0", "lessThan": "5.4", "versionType": "semver"}, {"status": "unaffected", "version": "5.4.120", "versionType": "semver", "lessThanOrEqual": "5.4.*"}, {"status": "unaffected", "version": "5.10.38", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.11.22", "versionType": "semver", "lessThanOrEqual": "5.11.*"}, {"status": "unaffected", "version": "5.12.5", "versionType": "semver", "lessThanOrEqual": "5.12.*"}, {"status": "unaffected", "version": "5.13", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["drivers/block/nbd.c"], "defaultStatus": "affected"}], "references": [{"url": "https://git.kernel.org/stable/c/1c4962df938891af9ab4775f5224ef8601764107"}, {"url": "https://git.kernel.org/stable/c/cde4b55cfb24522dcbba80bbdb0c082303e76c43"}, {"url": "https://git.kernel.org/stable/c/b31d237796fd618379ec8e0f4de3370b5e4aeee7"}, {"url": "https://git.kernel.org/stable/c/54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc"}, {"url": "https://git.kernel.org/stable/c/79ebe9110fa458d58f1fceb078e2068d7ad37390"}], "x_generator": {"engine": "bippy-1.2.0"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: Fix NULL pointer in flush_workqueue\n\nOpen /dev/nbdX first, the config_refs will be 1 and\nthe pointers in nbd_device are still null. Disconnect\n/dev/nbdX, then reference a null recv_workq. The\nprotection by config_refs in nbd_genl_disconnect is useless.\n\n[ 656.366194] BUG: kernel NULL pointer dereference, address: 0000000000000020\n[ 656.368943] #PF: supervisor write access in kernel mode\n[ 656.369844] #PF: error_code(0x0002) - not-present page\n[ 656.370717] PGD 10cc87067 P4D 10cc87067 PUD 1074b4067 PMD 0\n[ 656.371693] Oops: 0002 [#1] SMP\n[ 656.372242] CPU: 5 PID: 7977 Comm: nbd-client Not tainted 5.11.0-rc5-00040-g76c057c84d28 #1\n[ 656.373661] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014\n[ 656.375904] RIP: 0010:mutex_lock+0x29/0x60\n[ 656.376627] Code: 00 0f 1f 44 00 00 55 48 89 fd 48 83 05 6f d7 fe 08 01 e8 7a c3 ff ff 48 83 05 6a d7 fe 08 01 31 c0 65 48 8b 14 25 00 6d 01 00 <f0> 48 0f b1 55 d\n[ 656.378934] RSP: 0018:ffffc900005eb9b0 EFLAGS: 00010246\n[ 656.379350] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000\n[ 656.379915] RDX: ffff888104cf2600 RSI: ffffffffaae8f452 RDI: 0000000000000020\n[ 656.380473] RBP: 0000000000000020 R08: 0000000000000000 R09: ffff88813bd6b318\n[ 656.381039] R10: 00000000000000c7 R11: fefefefefefefeff R12: ffff888102710b40\n[ 656.381599] R13: ffffc900005eb9e0 R14: ffffffffb2930680 R15: ffff88810770ef00\n[ 656.382166] FS: 00007fdf117ebb40(0000) GS:ffff88813bd40000(0000) knlGS:0000000000000000\n[ 656.382806] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 656.383261] CR2: 0000000000000020 CR3: 0000000100c84000 CR4: 00000000000006e0\n[ 656.383819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n[ 656.384370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n[ 656.384927] Call Trace:\n[ 656.385111] flush_workqueue+0x92/0x6c0\n[ 656.385395] nbd_disconnect_and_put+0x81/0xd0\n[ 656.385716] nbd_genl_disconnect+0x125/0x2a0\n[ 656.386034] genl_family_rcv_msg_doit.isra.0+0x102/0x1b0\n[ 656.386422] genl_rcv_msg+0xfc/0x2b0\n[ 656.386685] ? nbd_ioctl+0x490/0x490\n[ 656.386954] ? genl_family_rcv_msg_doit.isra.0+0x1b0/0x1b0\n[ 656.387354] netlink_rcv_skb+0x62/0x180\n[ 656.387638] genl_rcv+0x34/0x60\n[ 656.387874] netlink_unicast+0x26d/0x590\n[ 656.388162] netlink_sendmsg+0x398/0x6c0\n[ 656.388451] ? netlink_rcv_skb+0x180/0x180\n[ 656.388750] ____sys_sendmsg+0x1da/0x320\n[ 656.389038] ? ____sys_recvmsg+0x130/0x220\n[ 656.389334] ___sys_sendmsg+0x8e/0xf0\n[ 656.389605] ? ___sys_recvmsg+0xa2/0xf0\n[ 656.389889] ? handle_mm_fault+0x1671/0x21d0\n[ 656.390201] __sys_sendmsg+0x6d/0xe0\n[ 656.390464] __x64_sys_sendmsg+0x23/0x30\n[ 656.390751] do_syscall_64+0x45/0x70\n[ 656.391017] entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\nTo fix it, just add if (nbd->recv_workq) to nbd_disconnect_and_put()."}], "cpeApplicability": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.4.120", "versionStartIncluding": "5.4"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.10.38", "versionStartIncluding": "5.4"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.11.22", "versionStartIncluding": "5.4"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.12.5", "versionStartIncluding": "5.4"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionEndExcluding": "5.13", "versionStartIncluding": "5.4"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionStartIncluding": "4.14.149"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionStartIncluding": "4.19.79"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "versionStartIncluding": "5.3.6"}], "operator": "OR"}]}], "providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-23T15:18:51.744Z"}}}, "cveMetadata": {"cveId": "CVE-2021-46981", "state": "PUBLISHED", "dateUpdated": "2026-05-23T15:18:51.744Z", "dateReserved": "2024-02-27T18:42:55.945Z", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "datePublished": "2024-02-28T08:13:10.972Z", "assignerShortName": "Linux"}, "dataVersion": "5.2"}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["drivers/block/nbd.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "1c4962df938891af9ab4775f5224ef8601764107", "status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "versionType": "git"}, {"lessThan": "cde4b55cfb24522dcbba80bbdb0c082303e76c43", "status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "versionType": "git"}, {"lessThan": "b31d237796fd618379ec8e0f4de3370b5e4aeee7", "status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "versionType": "git"}, {"lessThan": "54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc", "status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "versionType": "git"}, {"lessThan": "79ebe9110fa458d58f1fceb078e2068d7ad37390", "status": "affected", "version": "e9e006f5fcf2bab59149cb38a48a4817c1b538b4", "versionType": "git"}, {"status": "affected", "version": "0b584bf573ae59021069c056c22d65d5721910cb", "versionType": "git"}, {"status": "affected", "version": "9f0f39c92e4f50189155dfb13bb5524372e40eba", "versionType": "git"}, {"status": "affected", "version": "92ec11cccb7fc14331e000ab2337f60aa433433e", "versionType": "git"}, {"lessThan": "4.15", "status": "affected", "version": "4.14.149", "versionType": "semver"}, {"lessThan": "4.20", "status": "affected", "version": "4.19.79", "versionType": "semver"}, {"lessThan": "5.4", "status": "affected", "version": "5.3.6", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["drivers/block/nbd.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "5.4"}, {"lessThan": "5.4", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "5.4.*", "status": "unaffected", "version": "5.4.120", "versionType": "semver"}, {"lessThanOrEqual": "5.10.*", "status": "unaffected", "version": "5.10.38", "versionType": "semver"}, {"lessThanOrEqual": "5.11.*", "status": "unaffected", "version": "5.11.22", "versionType": "semver"}, {"lessThanOrEqual": "5.12.*", "status": "unaffected", "version": "5.12.5", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "5.13", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "74E02350-43FB-4F4F-B822-E9CA42371263", "versionEndExcluding": "5.4.120", "versionStartIncluding": "5.4", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "2BB4E5E8-4AAD-475A-A1B9-F287254C7D72", "versionEndExcluding": "5.10.38", "versionStartIncluding": "5.5", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "83B53E9A-F426-4C03-9A5F-A931FF79827E", "versionEndExcluding": "5.11.22", "versionStartIncluding": "5.11", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "matchCriteriaId": "0274929A-B36C-4F4C-AB22-30A0DD6B995B", "versionEndExcluding": "5.12.5", "versionStartIncluding": "5.12", "vulnerable": true}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:*", "matchCriteriaId": "0CBAD0FC-C281-4666-AB2F-F8E6E1165DF7", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnbd: Fix NULL pointer in flush_workqueue\n\nOpen /dev/nbdX first, the config_refs will be 1 and\nthe pointers in nbd_device are still null. Disconnect\n/dev/nbdX, then reference a null recv_workq. The\nprotection by config_refs in nbd_genl_disconnect is useless.\n\n[ 656.366194] BUG: kernel NULL pointer dereference, address: 0000000000000020\n[ 656.368943] #PF: supervisor write access in kernel mode\n[ 656.369844] #PF: error_code(0x0002) - not-present page\n[ 656.370717] PGD 10cc87067 P4D 10cc87067 PUD 1074b4067 PMD 0\n[ 656.371693] Oops: 0002 [#1] SMP\n[ 656.372242] CPU: 5 PID: 7977 Comm: nbd-client Not tainted 5.11.0-rc5-00040-g76c057c84d28 #1\n[ 656.373661] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014\n[ 656.375904] RIP: 0010:mutex_lock+0x29/0x60\n[ 656.376627] Code: 00 0f 1f 44 00 00 55 48 89 fd 48 83 05 6f d7 fe 08 01 e8 7a c3 ff ff 48 83 05 6a d7 fe 08 01 31 c0 65 48 8b 14 25 00 6d 01 00 <f0> 48 0f b1 55 d\n[ 656.378934] RSP: 0018:ffffc900005eb9b0 EFLAGS: 00010246\n[ 656.379350] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000\n[ 656.379915] RDX: ffff888104cf2600 RSI: ffffffffaae8f452 RDI: 0000000000000020\n[ 656.380473] RBP: 0000000000000020 R08: 0000000000000000 R09: ffff88813bd6b318\n[ 656.381039] R10: 00000000000000c7 R11: fefefefefefefeff R12: ffff888102710b40\n[ 656.381599] R13: ffffc900005eb9e0 R14: ffffffffb2930680 R15: ffff88810770ef00\n[ 656.382166] FS: 00007fdf117ebb40(0000) GS:ffff88813bd40000(0000) knlGS:0000000000000000\n[ 656.382806] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 656.383261] CR2: 0000000000000020 CR3: 0000000100c84000 CR4: 00000000000006e0\n[ 656.383819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n[ 656.384370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n[ 656.384927] Call Trace:\n[ 656.385111] flush_workqueue+0x92/0x6c0\n[ 656.385395] nbd_disconnect_and_put+0x81/0xd0\n[ 656.385716] nbd_genl_disconnect+0x125/0x2a0\n[ 656.386034] genl_family_rcv_msg_doit.isra.0+0x102/0x1b0\n[ 656.386422] genl_rcv_msg+0xfc/0x2b0\n[ 656.386685] ? nbd_ioctl+0x490/0x490\n[ 656.386954] ? genl_family_rcv_msg_doit.isra.0+0x1b0/0x1b0\n[ 656.387354] netlink_rcv_skb+0x62/0x180\n[ 656.387638] genl_rcv+0x34/0x60\n[ 656.387874] netlink_unicast+0x26d/0x590\n[ 656.388162] netlink_sendmsg+0x398/0x6c0\n[ 656.388451] ? netlink_rcv_skb+0x180/0x180\n[ 656.388750] ____sys_sendmsg+0x1da/0x320\n[ 656.389038] ? ____sys_recvmsg+0x130/0x220\n[ 656.389334] ___sys_sendmsg+0x8e/0xf0\n[ 656.389605] ? ___sys_recvmsg+0xa2/0xf0\n[ 656.389889] ? handle_mm_fault+0x1671/0x21d0\n[ 656.390201] __sys_sendmsg+0x6d/0xe0\n[ 656.390464] __x64_sys_sendmsg+0x23/0x30\n[ 656.390751] do_syscall_64+0x45/0x70\n[ 656.391017] entry_SYSCALL_64_after_hwframe+0x44/0xa9\n\nTo fix it, just add if (nbd->recv_workq) to nbd_disconnect_and_put()."}, {"lang": "es", "value": "En el kernel de Linux, se resolvi\u00f3 la siguiente vulnerabilidad: nbd: corrija el puntero NULL en flush_workqueue Abra /dev/nbdX primero, config_refs ser\u00e1 1 y los punteros en nbd_device seguir\u00e1n siendo nulos. Desconecte /dev/nbdX, luego haga referencia a un recv_workq nulo. La protecci\u00f3n de config_refs en nbd_genl_disconnect es in\u00fatil. [656.366194] ERROR: desreferencia del puntero NULL del kernel, direcci\u00f3n: 00000000000000020 [656.368943] #PF: acceso de escritura del supervisor en modo kernel [656.369844] #PF: c\u00f3digo_error(0x0002) - p\u00e1gina no presente [656.370717] PGD 10cc87067 P 4D 10cc87067 PUD 1074b4067 PMD 0 [656.371693] Ups: 0002 [#1] SMP [656.372242] CPU: 5 PID: 7977 Comm: nbd-client No contaminado 5.11.0-rc5-00040-g76c057c84d28 #1 [656.373661] Nombre de hardware: PC est\u00e1ndar QEMU (i 440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 01/04/2014 [ 656.375904] RIP: 0010:mutex_lock+0x29/0x60 [ 656.376627] C\u00f3digo: 00 0f 1f 44 00 00 55 48 89 fd 48 83 05 6f d7 fe 08 01 e8 7a c3 ff ff 48 83 05 6a d7 fe 08 01 31 c0 65 48 8b 14 25 00 6d 01 00 48 0f b1 55 d [ 656.378934 ] RSP: 0018:ffffc900005eb9b0 EFLAGS: 00010246 [ 656.379350] RAX: 0000000000000000 RBX: 00000000000000000 RCX: 0000000000000000 [ 656.379915 ] RDX: ffff888104cf2600 RSI: fffffffaae8f452 RDI: 0000000000000020 [ 656.380473] RBP: 00000000000000020 R08: 00000000000000000 R09: ffff88813bd6b31 8 [656.381039] R10: 00000000000000c7 R11: fefefefefefefeff R12: ffff888102710b40 [ 656.381599] R13: ffffc900005eb9e0 R14: ffffffffb2930680 R15: ffff88810770ef00 [ 656.3821 66] FS: 00007fdf117ebb40(0000) GS:ffff88813bd40000(0000) knlGS:0000000000000000 [ 656.382806] CS: 0010 DS: 0000 ES: 0000 CR0 : 0000000080050033 [ 656.383261] CR2: 0000000000000020 CR3: 0000000100c84000 CR4: 00000000000006e0 [ 656.383819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 656.384370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 656.384927] Seguimiento de llamadas : [656.385111] flux_workqueue+0x92 /0x6c0 [ 656.385395] nbd_disconnect_and_put+0x81/0xd0 [ 656.385716] nbd_genl_disconnect+0x125/0x2a0 [ 656.386034] genl_family_rcv_msg_doit.isra.0+0x102/0x1b0 [ 656 .386422] genl_rcv_msg+0xfc/0x2b0 [656.386685]? nbd_ioctl+0x490/0x490 [656.386954]? genl_family_rcv_msg_doit.isra.0+0x1b0/0x1b0 [ 656.387354] netlink_rcv_skb+0x62/0x180 [ 656.387638] genl_rcv+0x34/0x60 [ 656.387874] netlink_unicast+0x26d/0x590 [ 6 56.388162] netlink_sendmsg+0x398/0x6c0 [656.388451]? netlink_rcv_skb+0x180/0x180 [656.388750] ____sys_sendmsg+0x1da/0x320 [656.389038] ? ____sys_recvmsg+0x130/0x220 [ 656.389334] ___sys_sendmsg+0x8e/0xf0 [ 656.389605] ? ___sys_recvmsg+0xa2/0xf0 [656.389889] ? handle_mm_fault+0x1671/0x21d0 [ 656.390201] __sys_sendmsg+0x6d/0xe0 [ 656.390464] __x64_sys_sendmsg+0x23/0x30 [ 656.390751] do_syscall_64+0x45/0x70 [656.391017] Entry_SYSCALL_64_after_hwframe+0x44/0xa9 Para solucionarlo, simplemente agregue if (nbd-&gt;recv_workq) a nbd_disconnect_and_put()."}], "id": "CVE-2021-46981", "lastModified": "2026-06-17T04:16:03.980", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 5.5, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "version": "3.1"}, "exploitabilityScore": 1.8, "impactScore": 3.6, "source": "nvd@nist.gov", "type": "Primary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2021-46981", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "role": "CISA Coordinator", "timestamp": "2024-02-28T19:55:25.767523Z", "version": "2.0.3"}}]}, "published": "2024-02-28T09:15:37.320", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/1c4962df938891af9ab4775f5224ef8601764107"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/79ebe9110fa458d58f1fceb078e2068d7ad37390"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/b31d237796fd618379ec8e0f4de3370b5e4aeee7"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/cde4b55cfb24522dcbba80bbdb0c082303e76c43"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/1c4962df938891af9ab4775f5224ef8601764107"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/54b78ba7e96e5fe1edb8054e375d31a6c0dc60dc"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/79ebe9110fa458d58f1fceb078e2068d7ad37390"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/b31d237796fd618379ec8e0f4de3370b5e4aeee7"}, {"source": "af854a3a-2127-422b-91ae-364da2661108", "tags": ["Patch"], "url": "https://git.kernel.org/stable/c/cde4b55cfb24522dcbba80bbdb0c082303e76c43"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-476"}], "source": "nvd@nist.gov", "type": "Primary"}]}

{"bugzilla": {"description": "kernel: nbd: Fix NULL pointer in flush_workqueue", "id": "2266911", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2266911"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.4", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-476", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nnbd: Fix NULL pointer in flush_workqueue\nOpen /dev/nbdX first, the config_refs will be 1 and\nthe pointers in nbd_device are still null. Disconnect\n/dev/nbdX, then reference a null recv_workq. The\nprotection by config_refs in nbd_genl_disconnect is useless.\n[ 656.366194] BUG: kernel NULL pointer dereference, address: 0000000000000020\n[ 656.368943] #PF: supervisor write access in kernel mode\n[ 656.369844] #PF: error_code(0x0002) - not-present page\n[ 656.370717] PGD 10cc87067 P4D 10cc87067 PUD 1074b4067 PMD 0\n[ 656.371693] Oops: 0002 [#1] SMP\n[ 656.372242] CPU: 5 PID: 7977 Comm: nbd-client Not tainted 5.11.0-rc5-00040-g76c057c84d28 #1\n[ 656.373661] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014\n[ 656.375904] RIP: 0010:mutex_lock+0x29/0x60\n[ 656.376627] Code: 00 0f 1f 44 00 00 55 48 89 fd 48 83 05 6f d7 fe 08 01 e8 7a c3 ff ff 48 83 05 6a d7 fe 08 01 31 c0 65 48 8b 14 25 00 6d 01 00 <f0> 48 0f b1 55 d\n[ 656.378934] RSP: 0018:ffffc900005eb9b0 EFLAGS: 00010246\n[ 656.379350] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000\n[ 656.379915] RDX: ffff888104cf2600 RSI: ffffffffaae8f452 RDI: 0000000000000020\n[ 656.380473] RBP: 0000000000000020 R08: 0000000000000000 R09: ffff88813bd6b318\n[ 656.381039] R10: 00000000000000c7 R11: fefefefefefefeff R12: ffff888102710b40\n[ 656.381599] R13: ffffc900005eb9e0 R14: ffffffffb2930680 R15: ffff88810770ef00\n[ 656.382166] FS: 00007fdf117ebb40(0000) GS:ffff88813bd40000(0000) knlGS:0000000000000000\n[ 656.382806] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 656.383261] CR2: 0000000000000020 CR3: 0000000100c84000 CR4: 00000000000006e0\n[ 656.383819] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n[ 656.384370] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n[ 656.384927] Call Trace:\n[ 656.385111] flush_workqueue+0x92/0x6c0\n[ 656.385395] nbd_disconnect_and_put+0x81/0xd0\n[ 656.385716] nbd_genl_disconnect+0x125/0x2a0\n[ 656.386034] genl_family_rcv_msg_doit.isra.0+0x102/0x1b0\n[ 656.386422] genl_rcv_msg+0xfc/0x2b0\n[ 656.386685] ? nbd_ioctl+0x490/0x490\n[ 656.386954] ? genl_family_rcv_msg_doit.isra.0+0x1b0/0x1b0\n[ 656.387354] netlink_rcv_skb+0x62/0x180\n[ 656.387638] genl_rcv+0x34/0x60\n[ 656.387874] netlink_unicast+0x26d/0x590\n[ 656.388162] netlink_sendmsg+0x398/0x6c0\n[ 656.388451] ? netlink_rcv_skb+0x180/0x180\n[ 656.388750] ____sys_sendmsg+0x1da/0x320\n[ 656.389038] ? ____sys_recvmsg+0x130/0x220\n[ 656.389334] ___sys_sendmsg+0x8e/0xf0\n[ 656.389605] ? ___sys_recvmsg+0xa2/0xf0\n[ 656.389889] ? handle_mm_fault+0x1671/0x21d0\n[ 656.390201] __sys_sendmsg+0x6d/0xe0\n[ 656.390464] __x64_sys_sendmsg+0x23/0x30\n[ 656.390751] do_syscall_64+0x45/0x70\n[ 656.391017] entry_SYSCALL_64_after_hwframe+0x44/0xa9\nTo fix it, just add if (nbd->recv_workq) to nbd_disconnect_and_put()."], "name": "CVE-2021-46981", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2024-02-28T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-46981\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-46981\nhttps://lore.kernel.org/linux-cve-announce/2024022823-CVE-2021-46981-0fb9@gregkh/T/#u"], "threat_severity": "Moderate"}

{}