CVE-2026-98939

{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-98939", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.381Z", "datePublished": "2026-10-23T12:12:06.180Z", "dateUpdated": "2026-10-23T12:12:06.180Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-23T12:12:06.180Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/mm: Drop unnecessary PMD page copy when freeing\n\nOn a box with a discrete GPU, lockdep reports a possible deadlock as\nsoon as kswapd shrinks the TTM page pool. The immediate cause is an\nx86 commit that added an mmap_read_lock() to kernel page protection\nmunging code.\n\nThe huge vmap code holds the same lock over a GFP_KERNEL allocation,\nwhich is a no-no now that reclaim can take it. That allocation is in a\npage table *free* path and ends up being for dubious purposes[1].\nBasically, it tries to avoid hardware setting Accessed=1 in page table\nentries that are unreachable by the hardware, a non-issue.\n\nRemove the PMD copy. Detach the original PMD page at the PUD, flush\nthe mid-level caches, and free the PTE tables straight from the\ndetached PMD page. With no allocation left, the locking issue is gone.\n\nLockdep splat/analysis:\n\n WARNING: possible circular locking dependency detected\n 7.3.0-rc3-f6e7b42bf05b+ #183 Tainted: G U\n ------------------------------------------------------\n kswapd0/269 is trying to acquire lock:\n ((init_mm).mmap_lock){++++}-{4:4}, at: change_page_attr_set_clr+0x29a/0x4a0\n but task is already holding lock:\n (pool_shrink_rwsem){.+.+}-{4:4}, at: ttm_pool_shrink+0xb2/0x330 [ttm]\n Chain exists of:\n (init_mm).mmap_lock --> fs_reclaim --> pool_shrink_rwsem\n\nThe cycle is built from three edges:\n\n 1) pool_shrink_rwsem -> (init_mm).mmap_lock\n\n The TTM shrinker restores the caching attribute of every page it\n frees, while holding pool_shrink_rwsem:\n\n ttm_pool_shrink()\n -> ttm_pool_dispose_list()\n -> ttm_pool_free_page()\n -> set_pages_wb()\n -> change_page_attr_set_clr() [ init_mm mmap read lock ]\n\n 2) fs_reclaim -> pool_shrink_rwsem\n\n The same shrinker, called from reclaim.\n\n 3) (init_mm).mmap_lock -> fs_reclaim\n\n ioremap() installing a huge PUD mapping over an existing PMD table:\n\n ioremap_page_range()\n -> vmap_range_noflush()\n -> vmap_try_huge_pud() [ init_mm mmap read lock ]\n -> pud_free_pmd_page()\n -> __get_free_page(GFP_KERNEL) [ enters reclaim ]\n\n[ dhansen: Lots of changelog munging/trimming and merged comments from my\n\t version of the fix. ]"}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/x86/mm/pgtable.c"], "versions": [{"version": "e21a9ea81426a85fdb0cdcfcc99d5d9c16b402ab", "lessThan": "d3c2d2692bdf4af94bb27bc7a3aa0a348a567606", "status": "affected", "versionType": "git"}, {"version": "cc73b2043d106b467accd38e9b1fc09e0607c056", "lessThan": "f38c57a28ebbd057471573e39555d5aa11ab03cf", "status": "affected", "versionType": "git"}, {"version": "d5d8b8662e6e5a565b47a0388640e88402f23274", "lessThan": "e3ee38c1bc0b11a8d3e63dce7050759b61864286", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/x86/mm/pgtable.c"], "versions": [{"version": "6.18.53", "lessThan": "6.18.56", "status": "affected", "versionType": "semver"}, {"version": "7.2.7", "lessThan": "7.2.10", "status": "affected", "versionType": "semver"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.18.53", "versionEndExcluding": "6.18.56"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "7.2.7", "versionEndExcluding": "7.2.10"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/d3c2d2692bdf4af94bb27bc7a3aa0a348a567606"}, {"url": "https://git.kernel.org/stable/c/f38c57a28ebbd057471573e39555d5aa11ab03cf"}, {"url": "https://git.kernel.org/stable/c/e3ee38c1bc0b11a8d3e63dce7050759b61864286"}], "title": "x86/mm: Drop unnecessary PMD page copy when freeing", "x_generator": {"engine": "bippy-1.2.0"}}}}

{}

{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["arch/x86/mm/pgtable.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "d3c2d2692bdf4af94bb27bc7a3aa0a348a567606", "status": "affected", "version": "e21a9ea81426a85fdb0cdcfcc99d5d9c16b402ab", "versionType": "git"}, {"lessThan": "f38c57a28ebbd057471573e39555d5aa11ab03cf", "status": "affected", "version": "cc73b2043d106b467accd38e9b1fc09e0607c056", "versionType": "git"}, {"lessThan": "e3ee38c1bc0b11a8d3e63dce7050759b61864286", "status": "affected", "version": "d5d8b8662e6e5a565b47a0388640e88402f23274", "versionType": "git"}]}, {"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["arch/x86/mm/pgtable.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "6.18.56", "status": "affected", "version": "6.18.53", "versionType": "semver"}, {"lessThan": "7.2.10", "status": "affected", "version": "7.2.7", "versionType": "semver"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/mm: Drop unnecessary PMD page copy when freeing\n\nOn a box with a discrete GPU, lockdep reports a possible deadlock as\nsoon as kswapd shrinks the TTM page pool. The immediate cause is an\nx86 commit that added an mmap_read_lock() to kernel page protection\nmunging code.\n\nThe huge vmap code holds the same lock over a GFP_KERNEL allocation,\nwhich is a no-no now that reclaim can take it. That allocation is in a\npage table *free* path and ends up being for dubious purposes[1].\nBasically, it tries to avoid hardware setting Accessed=1 in page table\nentries that are unreachable by the hardware, a non-issue.\n\nRemove the PMD copy. Detach the original PMD page at the PUD, flush\nthe mid-level caches, and free the PTE tables straight from the\ndetached PMD page. With no allocation left, the locking issue is gone.\n\nLockdep splat/analysis:\n\n WARNING: possible circular locking dependency detected\n 7.3.0-rc3-f6e7b42bf05b+ #183 Tainted: G U\n ------------------------------------------------------\n kswapd0/269 is trying to acquire lock:\n ((init_mm).mmap_lock){++++}-{4:4}, at: change_page_attr_set_clr+0x29a/0x4a0\n but task is already holding lock:\n (pool_shrink_rwsem){.+.+}-{4:4}, at: ttm_pool_shrink+0xb2/0x330 [ttm]\n Chain exists of:\n (init_mm).mmap_lock --> fs_reclaim --> pool_shrink_rwsem\n\nThe cycle is built from three edges:\n\n 1) pool_shrink_rwsem -> (init_mm).mmap_lock\n\n The TTM shrinker restores the caching attribute of every page it\n frees, while holding pool_shrink_rwsem:\n\n ttm_pool_shrink()\n -> ttm_pool_dispose_list()\n -> ttm_pool_free_page()\n -> set_pages_wb()\n -> change_page_attr_set_clr() [ init_mm mmap read lock ]\n\n 2) fs_reclaim -> pool_shrink_rwsem\n\n The same shrinker, called from reclaim.\n\n 3) (init_mm).mmap_lock -> fs_reclaim\n\n ioremap() installing a huge PUD mapping over an existing PMD table:\n\n ioremap_page_range()\n -> vmap_range_noflush()\n -> vmap_try_huge_pud() [ init_mm mmap read lock ]\n -> pud_free_pmd_page()\n -> __get_free_page(GFP_KERNEL) [ enters reclaim ]\n\n[ dhansen: Lots of changelog munging/trimming and merged comments from my\n\t version of the fix. ]"}], "id": "CVE-2026-98939", "lastModified": "2026-10-23T13:17:14.843", "metrics": {}, "published": "2026-10-23T13:17:14.843", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/d3c2d2692bdf4af94bb27bc7a3aa0a348a567606"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/e3ee38c1bc0b11a8d3e63dce7050759b61864286"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f38c57a28ebbd057471573e39555d5aa11ab03cf"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: kernel: Denial of Service via circular locking dependency during page freeing", "id": "2559658", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2559658"}, "csaw": false, "cvss3": {"cvss3_base_score": "4.7", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-833", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nx86/mm: Drop unnecessary PMD page copy when freeing\nOn a box with a discrete GPU, lockdep reports a possible deadlock as\nsoon as kswapd shrinks the TTM page pool. The immediate cause is an\nx86 commit that added an mmap_read_lock() to kernel page protection\nmunging code.\nThe huge vmap code holds the same lock over a GFP_KERNEL allocation,\nwhich is a no-no now that reclaim can take it. That allocation is in a\npage table *free* path and ends up being for dubious purposes[1].\nBasically, it tries to avoid hardware setting Accessed=1 in page table\nentries that are unreachable by the hardware, a non-issue.\nRemove the PMD copy. Detach the original PMD page at the PUD, flush\nthe mid-level caches, and free the PTE tables straight from the\ndetached PMD page. With no allocation left, the locking issue is gone.\nLockdep splat/analysis:\nWARNING: possible circular locking dependency detected\n7.3.0-rc3-f6e7b42bf05b+ #183 Tainted: G U\n------------------------------------------------------\nkswapd0/269 is trying to acquire lock:\n((init_mm).mmap_lock){++++}-{4:4}, at: change_page_attr_set_clr+0x29a/0x4a0\nbut task is already holding lock:\n(pool_shrink_rwsem){.+.+}-{4:4}, at: ttm_pool_shrink+0xb2/0x330 [ttm]\nChain exists of:\n(init_mm).mmap_lock --> fs_reclaim --> pool_shrink_rwsem\nThe cycle is built from three edges:\n1) pool_shrink_rwsem -> (init_mm).mmap_lock\nThe TTM shrinker restores the caching attribute of every page it\nfrees, while holding pool_shrink_rwsem:\nttm_pool_shrink()\n-> ttm_pool_dispose_list()\n-> ttm_pool_free_page()\n-> set_pages_wb()\n-> change_page_attr_set_clr() [ init_mm mmap read lock ]\n2) fs_reclaim -> pool_shrink_rwsem\nThe same shrinker, called from reclaim.\n3) (init_mm).mmap_lock -> fs_reclaim\nioremap() installing a huge PUD mapping over an existing PMD table:\nioremap_page_range()\n-> vmap_range_noflush()\n-> vmap_try_huge_pud() [ init_mm mmap read lock ]\n-> pud_free_pmd_page()\n-> __get_free_page(GFP_KERNEL) [ enters reclaim ]\n[ dhansen: Lots of changelog munging/trimming and merged comments from my\nversion of the fix. ]", "A flaw was found in the Linux kernel's x86 memory management subsystem. Under memory pressure on systems with discrete graphics processing units (GPUs), a circular locking dependency can occur between memory reclamation and page table freeing routines. A local user could exploit this flaw to cause a kernel deadlock, resulting in a system freeze and Denial of Service (DoS)."], "name": "CVE-2026-98939", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"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": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Fix deferred", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "package_name": "openshift/ose-rhel-coreos-8", "product_name": "Red Hat OpenShift Container Platform 4"}, {"cpe": "cpe:/a:redhat:openshift:4", "fix_state": "Fix deferred", "package_name": "openshift/ose-rhel-coreos-9", "product_name": "Red Hat OpenShift Container Platform 4"}], "public_date": "2026-10-23T12:12:06Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-98939\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-98939\nhttps://git.kernel.org/stable/c/d3c2d2692bdf4af94bb27bc7a3aa0a348a567606\nhttps://git.kernel.org/stable/c/e3ee38c1bc0b11a8d3e63dce7050759b61864286\nhttps://git.kernel.org/stable/c/f38c57a28ebbd057471573e39555d5aa11ab03cf"], "threat_severity": "Moderate"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[e21a9ea81426a85fdb0cdcfcc99d5d9c16b402ab,d3c2d2692bdf4af94bb27bc7a3aa0a348a567606)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[cc73b2043d106b467accd38e9b1fc09e0607c056,f38c57a28ebbd057471573e39555d5aa11ab03cf)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[d5d8b8662e6e5a565b47a0388640e88402f23274,e3ee38c1bc0b11a8d3e63dce7050759b61864286)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[6.18.53,6.18.56)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[7.2.7,7.2.10)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[e21a9ea81426a85fdb0cdcfcc99d5d9c16b402ab,d3c2d2692bdf4af94bb27bc7a3aa0a348a567606)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[cc73b2043d106b467accd38e9b1fc09e0607c056,f38c57a28ebbd057471573e39555d5aa11ab03cf)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "code_commit", "value": "[d5d8b8662e6e5a565b47a0388640e88402f23274,e3ee38c1bc0b11a8d3e63dce7050759b61864286)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}, {"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[6.18.53,6.18.56)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[7.2.7,7.2.10)"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "Linux", "source": "cna", "vendor": "Linux"}, "product": "linux_kernel", "vendor": "linux"}], "created": "2026-10-23T14:45:17.883152+00:00", "updated": "2026-10-29T22:15:04.253152+00:00", "vendors": ["linux", "linux$PRODUCT$linux", "linux$PRODUCT$linux_kernel"]}