CVE-2025-39744rcu: Fix rcu_read_unlock() deadloop due to IRQ work
Updated under an hour ago ()
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In the Linux kernel, the following vulnerability has been resolved: rcu: Fix rcu_read_unlock() deadloop due to IRQ work During rcu_read_unlock_special(), if this happens during irq_exit(), we can lockup if an IPI is issued. This is because the IPI itself triggers the irq_exit() path causing a recursive lock up. This is precisely what Xiongfeng found when invoking a BPF program on the trace_tick_stop() tracepoint As shown in the trace below. Fix by managing the irq_work state correctly. irq_exit() __irq_exit_rcu() /* in_hardirq() returns false after this */ preempt_count_sub(HARDIRQ_OFFSET) tick_irq_exit() tick_nohz_irq_exit() tick_nohz_stop_sched_tick() trace_tick_stop() /* a bpf prog is hooked on this trace point */ __bpf_trace_tick_stop() bpf_trace_run2() rcu_read_unlock_special() /* will send a IPI to itself */ irq_work_queue_on(&rdp->defer_qs_iw, rdp->cpu); A simple reproducer can also be obtained by doing the following in tick_irq_exit(). It will hang on boot without the patch: static inline void tick_irq_exit(void) { + rcu_read_lock(); + WRITE_ONCE(current->rcu_read_unlock_special.b.need_qs, true); + rcu_read_unlock(); + [neeraj: Apply Frederic's suggested fix for PREEMPT_RT]
- CVSS
- 7.1 HIGH (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Analyzed
- Record last updated
- May 11, 2026
- First seen by InfoSec Signals
- Oct 19, 2026
Affected products
Linux Linux linux:linux (from the name) | from 0864f057b050bc6dd68106b3185e02db5140012d before e7a375453cca2b8a0d2fa1b82b913f3fed7c0507; 0864f057b050bc6dd68106b3185e02db5140012d builds before 1cfa244f7198d325594e627574930b7b91df5bfe; from 0864f057b050bc6dd68106b3185e02db5140012d before ddebb2a7677673cf4438a04e1a48b8ed6b0c8e9a; 0864f057b050bc6dd68106b3185e02db5140012d builds before 56c5ef194f4509df63fc0f7a91ea5973ce479b1e; from 0864f057b050bc6dd68106b3185e02db5140012d before b41642c87716bbd09797b1e4ea7d904f06c39b7b | CNA record |
linux linux_kernel linux:linux_kernel | before 6.6.103; from 6.7 before 6.12.43; from 6.13 before 6.15.11; from 6.16 before 6.16.2 | NVD |
References
- https://git.kernel.org/stable/c/e7a375453cca2b8a0d2fa1b82b913f3fed7c0507patch
- https://git.kernel.org/stable/c/1cfa244f7198d325594e627574930b7b91df5bfepatch
- https://git.kernel.org/stable/c/ddebb2a7677673cf4438a04e1a48b8ed6b0c8e9apatch
- https://git.kernel.org/stable/c/56c5ef194f4509df63fc0f7a91ea5973ce479b1epatch
- https://git.kernel.org/stable/c/b41642c87716bbd09797b1e4ea7d904f06c39b7bpatch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.