linux-kernel - [tip: perf/urgent] perf/core: Add RCU read lock protection to perf_iterate

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <174042219873.10177.3901726341080483847.tip-bot2@tip-bot2>
Date: Mon, 24 Feb 2025 18:36:38 -0000
From: "tip-bot2 for Breno Leitao" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Breno Leitao <leitao@...ian.org>, Ingo Molnar <mingo@...nel.org>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>, stable@...r.kernel.org,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: perf/urgent] perf/core: Add RCU read lock protection to
 perf_iterate_ctx()

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     0fe8813baf4b2e865d3b2c735ce1a15b86002c74
Gitweb:        https://git.kernel.org/tip/0fe8813baf4b2e865d3b2c735ce1a15b86002c74
Author:        Breno Leitao <leitao@...ian.org>
AuthorDate:    Fri, 17 Jan 2025 06:41:07 -08:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Mon, 24 Feb 2025 19:17:04 +01:00

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 ]

Fixes: bd2756811766 ("perf: Rewrite core context handling")
Signed-off-by: Breno Leitao <leitao@...ian.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: stable@...r.kernel.org
Link: https://lore.kernel.org/r/20250117-fix_perf_rcu-v1-1-13cb9210fc6a@debian.org
---
 kernel/events/core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index bcb09e0..7dabbca 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8321,7 +8321,8 @@ 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);