Linux KernelOperating system · Linux
CVE-2024-26732
A fix is available.
Upgrade to 6.7.7 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click
Patch available
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: net: implement lockless setsockopt(SO_PEEK_OFF) syzbot reported a lockdep violation [1] involving af_unix support of SO_PEEK_OFF. Since SO_PEEK_OFF is inherently not thread safe (it uses a per-socket sk_peek_off field), there is really no point to enforce a pointless thread safety in the kernel. After this patch : - setsockopt(SO_PEEK_OFF) no longer acquires the socket lock. - skb_consume_udp() no longer has to acquire the socket lock. - af_unix no longer needs a special version of sk_set_peek_off(), because it does not lock u->iolock anymore. As a followup, we could replace prot->set_peek_off to be a boolean and avoid an indirect call, since we always use sk_set_peek_off(). [1] WARNING: possible circular locking dependency detected 6.8.0-rc4-syzkaller-00267-g0f1dd5e91e2b #0 Not tainted syz-executor.2/30025 is trying to acquire lock: ffff8880765e7d80 (&u->iolock){+.+.}-{3:3}, at: unix_set_peek_off+0x26/0xa0 net/unix/af_unix.c:789 but task is already holding lock: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1691 [inline] ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1060 [inline] ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sk_setsockopt+0xe52/0x3360 net/core/sock.c:1193 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (sk_lock-AF_UNIX){+.+.}-{0:0}: lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 lock_sock_nested+0x48/0x100 net/core/sock.c:3524 lock_sock include/net/sock.h:1691 [inline] __unix_dgram_recvmsg+0x1275/0x12c0 net/unix/af_unix.c:2415 sock_recvmsg_nosec+0x18e/0x1d0 net/socket.c:1046 ____sys_recvmsg+0x3c0/0x470 net/socket.c:2801 ___sys_recvmsg net/socket.c:2845 [inline] do_recvmmsg+0x474/0xae0 net/socket.c:2939 __sys_recvmmsg net/socket.c:3018 [inline] __do_sys_recvmmsg net/socket.c:3041 [inline] __se_sys_recvmmsg net/socket.c:3034 [inline] __x64_sys_recvmmsg+0x199/0x250 net/socket.c:3034 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 -> #0 (&u->iolock){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3134 [inline] check_prevs_add kernel/locking/lockdep.c:3253 [inline] validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869 __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137 lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 unix_set_peek_off+0x26/0xa0 net/unix/af_unix.c:789 sk_setsockopt+0x207e/0x3360 do_sock_setsockopt+0x2fb/0x720 net/socket.c:2307 __sys_setsockopt+0x1ad/0x250 net/socket.c:2334 __do_sys_setsockopt net/socket.c:2343 [inline] __se_sys_setsockopt net/socket.c:2340 [inline] __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sk_lock-AF_UNIX); lock(&u->iolock); lock(sk_lock-AF_UNIX); lock(&u->iolock); *** DEADLOCK *** 1 lock held by syz-executor.2/30025: #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1691 [inline] #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1060 [inline] #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sk_setsockopt+0xe52/0x3360 net/core/sock.c:1193 stack backtrace: CPU: 0 PID: 30025 Comm: syz-executor.2 Not tainted 6.8.0-rc4-syzkaller-00267-g0f1dd5e91e2b #0 Hardware name: Google Google C ---truncated---
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis
How this class of weakness works · CWE-667
Shared resources are accessed without correct locking, so concurrent operations interleave into inconsistent — and sometimes exploitable — states, or deadlock the service outright. These bugs are subtle and timing-dependent. The fix is correct, consistent locking or atomic operations around every shared resource.
General guidance for the improper locking class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Linux KernelOperating system
Affected:
>= 6.7, < 6.7.7= 6.8CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped
Upgrade available
Upgrade to 6.7.7 or later
Fixed in
6.7.7
Vendor patch
git.kernel.org →
Recommended fix
High confidence
Linux Kernel 6.7.7 or later, or 6.9+
- Upgrade Linux kernel to version 6.7.7 or later, or 6.9 or later to resolve the circular locking dependency
Generated from the published advisory — verify against the referenced sources before acting.
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Free · runs locally
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2024-26732 in production — separate from our analysis above.
Know something about CVE-2024-26732?
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