{"cve":"CVE-2024-49946","nvd":{"published":"2024-10-21T18:15:16.133","modified":"2026-06-17T08:00:47.537","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nppp: do not assume bh is held in ppp_channel_bridge_input()\n\nNetworking receive path is usually handled from BH handler.\nHowever, some protocols need to acquire the socket lock, and\npackets might be stored in the socket backlog is the socket was\nowned by a user process.\n\nIn this case, release_sock(), __release_sock(), and sk_backlog_rcv()\nmight call the sk->sk_backlog_rcv() handler in process context.\n\nsybot caught ppp was not considering this case in\nppp_channel_bridge_input() :\n\nWARNING: inconsistent lock state\n6.11.0-rc7-syzkaller-g5f5673607153 #0 Not tainted\n--------------------------------\ninconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.\nksoftirqd/1/24 [HC0[0]:SC1[1]:HE1:SE0] takes:\n ffff0000db7f11e0 (&pch->downl){+.?.}-{2:2}, at: spin_lock include/linux/spinlock.h:351 [inline]\n ffff0000db7f11e0 (&pch->downl){+.?.}-{2:2}, at: ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]\n ffff0000db7f11e0 (&pch->downl){+.?.}-{2:2}, at: ppp_input+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304\n{SOFTIRQ-ON-W} state was registered at:\n   lock_acquire+0x240/0x728 kernel/locking/lockdep.c:5759\n   __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]\n   _raw_spin_lock+0x48/0x60 kernel/locking/spinlock.c:154\n   spin_lock include/linux/spinlock.h:351 [inline]\n   ppp_channel_bridge_input drivers/net/ppp/ppp_generic.c:2272 [inline]\n   ppp_input+0x16c/0x854 drivers/net/ppp/ppp_generic.c:2304\n   pppoe_rcv_core+0xfc/0x314 drivers/net/ppp/pppoe.c:379\n   sk_backlog_rcv include/net/sock.h:1111 [inline]\n   __release_sock+0x1a8/0x3d8 net/core/sock.c:3004\n   release_sock+0x68/0x1b8 net/core/sock.c:3558\n   pppoe_sendmsg+0xc8/0x5d8 drivers/net/ppp/pppoe.c:903\n   sock_sendmsg_nosec net/socket.c:730 [inline]\n   __sock_sendmsg net/socket.c:745 [inline]\n   __sys_sendto+0x374/0x4f4 net/socket.c:2204\n   __do_sys_sendto net/socket.c:2216 [inline]\n   __se_sys_sendto net/socket.c:2212 [inline]\n   __arm64_sys_sendto+0xd8/0xf8 net/socket.c:2212\n   __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]\n   invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49\n   el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132\n   do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151\n   el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:712\n   el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730\n   el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598\nirq event stamp: 282914\n hardirqs last  enabled at (282914): [<ffff80008b42e30c>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline]\n hardirqs last  enabled at (282914): [<ffff80008b42e30c>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:194\n hardirqs last disabled at (282913): [<ffff80008b42e13c>] __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:108 [inline]\n hardirqs last disabled at (282913): [<ffff80008b42e13c>] _raw_spin_lock_irqsave+0x2c/0x7c kernel/locking/spinlock.c:162\n softirqs last  enabled at (282904): [<ffff8000801f8e88>] softirq_handle_end kernel/softirq.c:400 [inline]\n softirqs last  enabled at (282904): [<ffff8000801f8e88>] handle_softirqs+0xa3c/0xbfc kernel/softirq.c:582\n softirqs last disabled at (282909): [<ffff8000801fbdf8>] run_ksoftirqd+0x70/0x158 kernel/softirq.c:928\n\nother info that might help us debug this:\n Possible unsafe locking scenario:\n\n       CPU0\n       ----\n  lock(&pch->downl);\n  <Interrupt>\n    lock(&pch->downl);\n\n *** DEADLOCK ***\n\n1 lock held by ksoftirqd/1/24:\n  #0: ffff80008f74dfa0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x10/0x4c include/linux/rcupdate.h:325\n\nstack backtrace:\nCPU: 1 UID: 0 PID: 24 Comm: ksoftirqd/1 Not tainted 6.11.0-rc7-syzkaller-g5f5673607153 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024\nCall trace:\n  dump_backtrace+0x1b8/0x1e4 arch/arm64/kernel/stacktrace.c:319\n  show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:326\n  __dump_sta\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":[],"references":["https://git.kernel.org/stable/c/176dd41e8c2bd997ed3d66568a3362e69ecce99b","https://git.kernel.org/stable/c/635deca1800a68624f185dc1e04a8495b48cf185","https://git.kernel.org/stable/c/aec7291003df78cb71fd461d7b672912bde55807","https://git.kernel.org/stable/c/c837f8583535f094a39386308c2ccfd92c8596cd","https://git.kernel.org/stable/c/efe9cc0f7c0279216a5522271ec675b8288602e4"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:56:33.105311382+00:00"},"epss":{"cve":"CVE-2024-49946","score":0.00236,"percentile":0.14608,"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."]}