cbcvebase.
CVE-2025-39744
published 2025-09-11

CVE-2025-39744: 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…

PriorityP427high7.1CVSS 3.1
AVLACLPRLUINSUCHINAH
EPSS
0.15%
4.6th percentile
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

27 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.16.3-1 (forky)linux 6.16.3-1 (forky)
linuxlinux
linuxlinux>= 0864f057b050bc6dd68106b3185e02db5140012d < e7a375453cca2b8a0d2fa1b82b913f3fed7c0507e7a375453cca2b8a0d2fa1b82b913f3fed7c0507
linuxlinux>= 0864f057b050bc6dd68106b3185e02db5140012d < 1cfa244f7198d325594e627574930b7b91df5bfe1cfa244f7198d325594e627574930b7b91df5bfe
linuxlinux>= 0864f057b050bc6dd68106b3185e02db5140012d < ddebb2a7677673cf4438a04e1a48b8ed6b0c8e9addebb2a7677673cf4438a04e1a48b8ed6b0c8e9a
linuxlinux>= 0864f057b050bc6dd68106b3185e02db5140012d < 56c5ef194f4509df63fc0f7a91ea5973ce479b1e56c5ef194f4509df63fc0f7a91ea5973ce479b1e
linuxlinux>= 0864f057b050bc6dd68106b3185e02db5140012d < b41642c87716bbd09797b1e4ea7d904f06c39b7bb41642c87716bbd09797b1e4ea7d904f06c39b7b
linuxlinux_kernel< 6.6.1036.6.103
linuxlinux_kernel>= 0 < 6.12.43-16.12.43-1
linuxlinux_kernel>= 0 < 6.16.3-16.16.3-1
linuxlinux_kernel>= 0 < 6.8.0-100.1006.8.0-100.100
linuxlinux_kernel>= 6.13 < 6.15.116.15.11
linuxlinux_kernel>= 6.16 < 6.16.26.16.2
linuxlinux_kernel>= 6.7 < 6.12.436.12.43
msrcazl3_kernel_6.6.96.2-2_on_azure_linux_3.0
msrccbl2_kernel_5.15.186.1-1_on_cbl_mariner_2.0
msrccbl2_kernel_5.15.200.1-1_on_cbl_mariner_2.0
msrccbl2_kernel_5.15.202.1-1_on_cbl_mariner_2.0
ubuntulinux-aws
ubuntulinux-aws-6.8
ubuntulinux-gkeop
ubuntulinux-nvidia
ubuntulinux-nvidia-6.8
ubuntulinux-oracle
ubuntulinux-oracle-6.8

CVSS provenance

nvdv3.17.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
osv7.1HIGH
vendor_debian7.1HIGH
vendor_redhat7.1HIGH
vendor_msrc5.5MEDIUM
vendor_ubuntu3.2LOW
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