CVE-2025-21889 Information

Description

In the Linux kernel the following vulnerability has been resolved:

perf/core: Add RCU read lock protection to perf_iterate_ctx()

The perf_iterate_ctx() function performs RCU list traversal but currently lacks RCU read lock protection. This causes lockdep warnings when running perf probe with unshare(1) under CONFIG_PROVE_RCU_LIST=y:

WARNING: suspicious RCU usage
kernel/events/core.c:8168 RCU-list traversed in non-reader section!!

 Call Trace:
  lockdep_rcu_suspicious
  ? perf_event_addr_filters_apply
  perf_iterate_ctx
  perf_event_exec
  begin_new_exec
  ? load_elf_phdrs
  load_elf_binary
  ? lock_acquire
  ? find_held_lock
  ? bprm_execve
  bprm_execve
  do_execveat_common.isra.0
  __x64_sys_execve
  do_syscall_64
  entry_SYSCALL_64_after_hwframe

This protection was previously present but was removed in commit bd2756811766 (\perf: Rewrite core context handling). Add back the necessary rcu_read_lock()/rcu_read_unlock() pair around perf_iterate_ctx() call in perf_event_exec().

[ mingo: Use scoped_guard() as suggested by Peter ]

Reference

https://git.kernel.org/stable/c/0fe8813baf4b2e865d3b2c735ce1a15b86002c74 https://git.kernel.org/stable/c/a2475ccad6120546ea45dbcd6cd1f74dc565ef6b https://git.kernel.org/stable/c/dd536566dda9a551fc2a2acfab5313a5bb13ed02 https://git.kernel.org/stable/c/f390c2eea571945f357a2d3b9fcb1c015767132e