CVE-2024-35892
Vulnerability Scoring
Status: Awaiting Analysis
Last updated: 🕘 21 Nov 2024, 09:21 UTC
Originally published on: 🕘 19 May 2024, 09:15 UTC
Time between publication and last update: 186 days
CVSS Release:
CVE-2024-35892: In the Linux kernel, the following vulnerability has been resolved: net/sched: fix lockdep splat in qdisc_tree_reduce_backlog() qdisc_tree_reduce_backlog() is called with the qdisc lock held, not RTNL. We must use qdisc_lookup_rcu() instead of qdisc_lookup() syzbot reported: WARNING: suspicious RCU usage 6.1.74-syzkaller #0 Not tainted ----------------------------- net/sched/sch_api.c:305 suspicious rcu_dereference_protected() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 3 locks held by udevd/1142: #0: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:306 [inline] #0: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline] #0: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: net_tx_action+0x64a/0x970 net/core/dev.c:5282 #1: ffff888171861108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline] #1: ffff888171861108 (&sch->q.lock){+.-.}-{2:2}, at: net_tx_action+0x754/0x970 net/core/dev.c:5297 #2: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:306 [inline] #2: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline] #2: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: qdisc_tree_reduce_backlog+0x84/0x580 net/sched/sch_api.c:792 stack backtrace: CPU: 1 PID: 1142 Comm: udevd Not tainted 6.1.74-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 Call Trace: <TASK> [<ffffffff85b85f14>] __dump_stack lib/dump_stack.c:88 [inline] [<ffffffff85b85f14>] dump_stack_lvl+0x1b1/0x28f lib/dump_stack.c:106 [<ffffffff85b86007>] dump_stack+0x15/0x1e lib/dump_stack.c:113 [<ffffffff81802299>] lockdep_rcu_suspicious+0x1b9/0x260 kernel/locking/lockdep.c:6592 [<ffffffff84f0054c>] qdisc_lookup+0xac/0x6f0 net/sched/sch_api.c:305 [<ffffffff84f037c3>] qdisc_tree_reduce_backlog+0x243/0x580 net/sched/sch_api.c:811 [<ffffffff84f5b78c>] pfifo_tail_enqueue+0x32c/0x4b0 net/sched/sch_fifo.c:51 [<ffffffff84fbcf63>] qdisc_enqueue include/net/sch_generic.h:833 [inline] [<ffffffff84fbcf63>] netem_dequeue+0xeb3/0x15d0 net/sched/sch_netem.c:723 [<ffffffff84eecab9>] dequeue_skb net/sched/sch_generic.c:292 [inline] [<ffffffff84eecab9>] qdisc_restart net/sched/sch_generic.c:397 [inline] [<ffffffff84eecab9>] __qdisc_run+0x249/0x1e60 net/sched/sch_generic.c:415 [<ffffffff84d7aa96>] qdisc_run+0xd6/0x260 include/net/pkt_sched.h:125 [<ffffffff84d85d29>] net_tx_action+0x7c9/0x970 net/core/dev.c:5313 [<ffffffff85e002bd>] __do_softirq+0x2bd/0x9bd kernel/softirq.c:616 [<ffffffff81568bca>] invoke_softirq kernel/softirq.c:447 [inline] [<ffffffff81568bca>] __irq_exit_rcu+0xca/0x230 kernel/softirq.c:700 [<ffffffff81568ae9>] irq_exit_rcu+0x9/0x20 kernel/softirq.c:712 [<ffffffff85b89f52>] sysvec_apic_timer_interrupt+0x42/0x90 arch/x86/kernel/apic/apic.c:1107 [<ffffffff85c00ccb>] asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:656
The exploitability of CVE-2024-35892 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).
No exploitability data is available for CVE-2024-35892.
A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.
Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.
Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.
Above is the CVSS Sub-score Breakdown for CVE-2024-35892, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.
Below is the Impact Analysis for CVE-2024-35892, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.
The EPSS score estimates the probability that this vulnerability will be exploited in the near future.
EPSS Score: 0.045% (probability of exploit)
EPSS Percentile: 18.35%
(lower percentile = lower relative risk)
This vulnerability is less risky than approximately 81.65% of others.
Unknown
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