CVE-2021-47598

sch_cake: do not call cake_destroy() from cake_init()

Published Jun 19, 2024 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

sch_cake: do not call cake_destroy() from cake_init()

qdiscs are not supposed to call their own destroy() method
from init(), because core stack already does that.

syzbot was able to trigger use after free:

DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: CPU: 0 PID: 21902 at kernel/locking/mutex.c:586 __mutex_lock_common kernel/locking/mutex.c:586 [inline]
WARNING: CPU: 0 PID: 21902 at kernel/locking/mutex.c:586 __mutex_lock+0x9ec/0x12f0 kernel/locking/mutex.c:740
Modules linked in:
CPU: 0 PID: 21902 Comm: syz-executor189 Not tainted 5.16.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:__mutex_lock_common kernel/locking/mutex.c:586 [inline]
RIP: 0010:__mutex_lock+0x9ec/0x12f0 kernel/locking/mutex.c:740
Code: 08 84 d2 0f 85 19 08 00 00 8b 05 97 38 4b 04 85 c0 0f 85 27 f7 ff ff 48 c7 c6 20 00 ac 89 48 c7 c7 a0 fe ab 89 e8 bf 76 ba ff <0f> 0b e9 0d f7 ff ff 48 8b 44 24 40 48 8d b8 c8 08 00 00 48 89 f8
RSP: 0018:ffffc9000627f290 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88802315d700 RSI: ffffffff815f1db8 RDI: fffff52000c4fe44
RBP: ffff88818f28e000 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815ebb5e R11: 0000000000000000 R12: 0000000000000000
R13: dffffc0000000000 R14: ffffc9000627f458 R15: 0000000093c30000
FS: 0000555556abc400(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fda689c3303 CR3: 000000001cfbb000 CR4: 0000000000350ef0
Call Trace:
<TASK>
tcf_chain0_head_change_cb_del+0x2e/0x3d0 net/sched/cls_api.c:810
tcf_block_put_ext net/sched/cls_api.c:1381 [inline]
tcf_block_put_ext net/sched/cls_api.c:1376 [inline]
tcf_block_put+0xbc/0x130 net/sched/cls_api.c:1394
cake_destroy+0x3f/0x80 net/sched/sch_cake.c:2695
qdisc_create.constprop.0+0x9da/0x10f0 net/sched/sch_api.c:1293
tc_modify_qdisc+0x4c5/0x1980 net/sched/sch_api.c:1660
rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5571
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2496
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x904/0xdf0 net/netlink/af_netlink.c:1921
sock_sendmsg_nosec net/socket.c:704 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:724
____sys_sendmsg+0x6e8/0x810 net/socket.c:2409
___sys_sendmsg+0xf3/0x170 net/socket.c:2463
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2492
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f1bb06badb9
Code: Unable to access opcode bytes at RIP 0x7f1bb06bad8f.
RSP: 002b:00007fff3012a658 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f1bb06badb9
RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000003
R10: 0000000000000003 R11: 0000000000000246 R12: 00007fff3012a688
R13: 00007fff3012a6a0 R14: 00007fff3012a6e0 R15: 00000000000013c2
</TASK>

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
Metrics cvssV3_1

{'score': 5.6, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Aug 5, 2026, 8:48 AM
Reserved
May 24, 2024, 3:11 PM
Status
Modified
Published
Jun 19, 2024, 3:15 PM
Modified
Aug 4, 2026, 10:17 AM
Severity
Moderate
Public date
Jun 19, 2024, 12:00 AM