From: Breno Leitao Date: Fri, 17 Jan 2025 14:41:07 +0000 (-0800) Subject: perf/core: Add RCU read lock protection to perf_iterate_ctx() X-Git-Tag: v6.12.18~60 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a2475ccad6120546ea45dbcd6cd1f74dc565ef6b;p=thirdparty%2Fkernel%2Fstable.git perf/core: Add RCU read lock protection to perf_iterate_ctx() commit 0fe8813baf4b2e865d3b2c735ce1a15b86002c74 upstream. 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 ] Fixes: bd2756811766 ("perf: Rewrite core context handling") Signed-off-by: Breno Leitao Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250117-fix_perf_rcu-v1-1-13cb9210fc6a@debian.org Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/events/core.c b/kernel/events/core.c index 07cd2dbab0e88..a3db8f859c7a2 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8240,7 +8240,8 @@ void perf_event_exec(void) perf_event_enable_on_exec(ctx); perf_event_remove_on_exec(ctx); - perf_iterate_ctx(ctx, perf_event_addr_filters_exec, NULL, true); + scoped_guard(rcu) + perf_iterate_ctx(ctx, perf_event_addr_filters_exec, NULL, true); perf_unpin_context(ctx); put_ctx(ctx);