CVE-2026-74337

About vulnerability

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix NMI/tracepoint re-entry deadlock on lru locks

NMI and tracepoint BPF programs can re-enter the per-CPU or global LRU lock that bpf_lru_pop_free()/push_free() already hold on the same CPU, AA-deadlocking. Lockdep reports “inconsistent {INITIAL USE} -> {IN-NMI}” on &l->lock (syzbot c69a0a2c816716f1e0d5) and “possible recursive locking detected” on &loc_l->lock (syzbot 18b26edb69b2e19f3b33).

Prior trylock and rqspinlock based fixes (see links) were nacked because compromised on reliability.

This patch converts every LRU lock site to rqspinlock_t and adds a recovery path for some failure windows to avoid node leaks.

Failure recovery:

• *_pop_free top-level: return NULL; prealloc_lru_pop() already treats that as no-free-element (-ENOMEM).

• Cross-CPU steal: skip the victim’s locked loc_l, try next CPU.

• Post-steal local lock fail: publish stolen node to lockless per-CPU free_llist; next pop on this CPU picks it up.

• push_free fail: mark node pending_free=1. __local_list_flush(), __local_list_pop_pending() reclaim the node from pending_list. __bpf_lru_list_shrink_inactive() reclaims the node from inactive list. Nodes from active list are reclaimed by __bpf_lru_list_shrink() or after __bpf_lru_list_rotate_active() demotes it to the inactive.

Affected product:

AlmaLinux 9.2 ESU , Amazon Linux 2 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CentOS Stream 8 ELS , CloudLinux 7 ELS , Debian 10 ELS , Debian 11 ELS , Oracle Linux 7 ELS , RHEL 7 ELS , TuxCare 9.6 ESU , TuxCare 9.8 ESU , Ubuntu 16.04 ELS , Ubuntu 18.04 ELS , Ubuntu 20.04 ELS

Affected packages:

linux @ 4.19.0 (+16 more)

Live-patch status from KernelCare for each operating system.