{"cve":"CVE-2024-26732","nvd":{"published":"2024-04-03T17:15:50.977","modified":"2026-06-17T07:18:12.100","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: implement lockless setsockopt(SO_PEEK_OFF)\n\nsyzbot reported a lockdep violation [1] involving af_unix\nsupport of SO_PEEK_OFF.\n\nSince SO_PEEK_OFF is inherently not thread safe (it uses a per-socket\nsk_peek_off field), there is really no point to enforce a pointless\nthread safety in the kernel.\n\nAfter this patch :\n\n- setsockopt(SO_PEEK_OFF) no longer acquires the socket lock.\n\n- skb_consume_udp() no longer has to acquire the socket lock.\n\n- af_unix no longer needs a special version of sk_set_peek_off(),\n  because it does not lock u->iolock anymore.\n\nAs a followup, we could replace prot->set_peek_off to be a boolean\nand avoid an indirect call, since we always use sk_set_peek_off().\n\n[1]\n\nWARNING: possible circular locking dependency detected\n6.8.0-rc4-syzkaller-00267-g0f1dd5e91e2b #0 Not tainted\n\nsyz-executor.2/30025 is trying to acquire lock:\n ffff8880765e7d80 (&u->iolock){+.+.}-{3:3}, at: unix_set_peek_off+0x26/0xa0 net/unix/af_unix.c:789\n\nbut task is already holding lock:\n ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1691 [inline]\n ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1060 [inline]\n ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sk_setsockopt+0xe52/0x3360 net/core/sock.c:1193\n\nwhich lock already depends on the new lock.\n\nthe existing dependency chain (in reverse order) is:\n\n-> #1 (sk_lock-AF_UNIX){+.+.}-{0:0}:\n        lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754\n        lock_sock_nested+0x48/0x100 net/core/sock.c:3524\n        lock_sock include/net/sock.h:1691 [inline]\n        __unix_dgram_recvmsg+0x1275/0x12c0 net/unix/af_unix.c:2415\n        sock_recvmsg_nosec+0x18e/0x1d0 net/socket.c:1046\n        ____sys_recvmsg+0x3c0/0x470 net/socket.c:2801\n        ___sys_recvmsg net/socket.c:2845 [inline]\n        do_recvmmsg+0x474/0xae0 net/socket.c:2939\n        __sys_recvmmsg net/socket.c:3018 [inline]\n        __do_sys_recvmmsg net/socket.c:3041 [inline]\n        __se_sys_recvmmsg net/socket.c:3034 [inline]\n        __x64_sys_recvmmsg+0x199/0x250 net/socket.c:3034\n       do_syscall_64+0xf9/0x240\n       entry_SYSCALL_64_after_hwframe+0x6f/0x77\n\n-> #0 (&u->iolock){+.+.}-{3:3}:\n        check_prev_add kernel/locking/lockdep.c:3134 [inline]\n        check_prevs_add kernel/locking/lockdep.c:3253 [inline]\n        validate_chain+0x18ca/0x58e0 kernel/locking/lockdep.c:3869\n        __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137\n        lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754\n        __mutex_lock_common kernel/locking/mutex.c:608 [inline]\n        __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752\n        unix_set_peek_off+0x26/0xa0 net/unix/af_unix.c:789\n       sk_setsockopt+0x207e/0x3360\n        do_sock_setsockopt+0x2fb/0x720 net/socket.c:2307\n        __sys_setsockopt+0x1ad/0x250 net/socket.c:2334\n        __do_sys_setsockopt net/socket.c:2343 [inline]\n        __se_sys_setsockopt net/socket.c:2340 [inline]\n        __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340\n       do_syscall_64+0xf9/0x240\n       entry_SYSCALL_64_after_hwframe+0x6f/0x77\n\nother info that might help us debug this:\n\n Possible unsafe locking scenario:\n\n       CPU0                    CPU1\n       ----                    ----\n  lock(sk_lock-AF_UNIX);\n                               lock(&u->iolock);\n                               lock(sk_lock-AF_UNIX);\n  lock(&u->iolock);\n\n *** DEADLOCK ***\n\n1 lock held by syz-executor.2/30025:\n  #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1691 [inline]\n  #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sockopt_lock_sock net/core/sock.c:1060 [inline]\n  #0: ffff8880765e7930 (sk_lock-AF_UNIX){+.+.}-{0:0}, at: sk_setsockopt+0xe52/0x3360 net/core/sock.c:1193\n\nstack backtrace:\nCPU: 0 PID: 30025 Comm: syz-executor.2 Not tainted 6.8.0-rc4-syzkaller-00267-g0f1dd5e91e2b #0\nHardware name: Google Google C\n---truncated---","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-667"],"references":["https://git.kernel.org/stable/c/56667da7399eb19af857e30f41bea89aa6fa812c","https://git.kernel.org/stable/c/897f75e2cde8a5f9f7529b55249af1fa4248c83b","https://git.kernel.org/stable/c/56667da7399eb19af857e30f41bea89aa6fa812c","https://git.kernel.org/stable/c/897f75e2cde8a5f9f7529b55249af1fa4248c83b"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:47:51.568503435+00:00"},"epss":{"cve":"CVE-2024-26732","score":0.00158,"percentile":0.0489,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}