{ "data_version": "4.0", "data_type": "CVE", "data_format": "MITRE", "CVE_data_meta": { "ID": "CVE-2024-26732", "ASSIGNER": "cve@kernel.org", "STATE": "PUBLIC" }, "description": { "description_data": [ { "lang": "eng", "value": "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---" } ] }, "problemtype": { "problemtype_data": [ { "description": [ { "lang": "eng", "value": "n/a" } ] } ] }, "affects": { "vendor": { "vendor_data": [ { "vendor_name": "Linux", "product": { "product_data": [ { "product_name": "Linux", "version": { "version_data": [ { "version_affected": "<", "version_name": "859051dd165e", "version_value": "897f75e2cde8" }, { "version_value": "not down converted", "x_cve_json_5_version_data": { "versions": [ { "version": "6.7", "status": "affected" }, { "version": "0", "lessThan": "6.7", "status": "unaffected", "versionType": "custom" }, { "version": "6.7.7", "lessThanOrEqual": "6.7.*", "status": "unaffected", "versionType": "custom" }, { "version": "6.8", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ], "defaultStatus": "affected" } } ] } } ] } } ] } }, "references": { "reference_data": [ { "url": "https://git.kernel.org/stable/c/897f75e2cde8a5f9f7529b55249af1fa4248c83b", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/897f75e2cde8a5f9f7529b55249af1fa4248c83b" }, { "url": "https://git.kernel.org/stable/c/56667da7399eb19af857e30f41bea89aa6fa812c", "refsource": "MISC", "name": "https://git.kernel.org/stable/c/56667da7399eb19af857e30f41bea89aa6fa812c" } ] }, "generator": { "engine": "bippy-a5840b7849dd" } }