Description (CNA)
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]
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 0864f057b050bc6dd68106b3185e02db5140012d before e7a375453cca2b8a0d2fa1b82b913f3fed7c0507; affected 0864f057b050bc6dd68106b3185e02db5140012d before 1cfa244f7198d325594e627574930b7b91df5bfe; affected 0864f057b050bc6dd68106b3185e02db5140012d before ddebb2a7677673cf4438a04e1a48b8ed6b0c8e9a; affected 0864f057b050bc6dd68106b3185e02db5140012d before 56c5ef194f4509df63fc0f7a91ea5973ce479b1e; affected 0864f057b050bc6dd68106b3185e02db5140012d before b41642c87716bbd09797b1e4ea7d904f06c39b7b |
| Linux / Linux | affected 5.3; unaffected 0 before 5.3; unaffected 6.6.103 through 6.6.*; unaffected 6.12.43 through 6.12.*; unaffected 6.15.11 through 6.15.*; unaffected 6.16.2 through 6.16.*; unaffected 6.17 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/e7a375453cca2b8a0d2fa1b82b913f3fed7c0507
- https://git.kernel.org/stable/c/1cfa244f7198d325594e627574930b7b91df5bfe
- https://git.kernel.org/stable/c/ddebb2a7677673cf4438a04e1a48b8ed6b0c8e9a
- https://git.kernel.org/stable/c/56c5ef194f4509df63fc0f7a91ea5973ce479b1e
- https://git.kernel.org/stable/c/b41642c87716bbd09797b1e4ea7d904f06c39b7b