This is a note to let you know that I've just added the patch titled
bpf: Fixes possible race in update_prog_stats() for 32bit arches
to the 5.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bpf-fixes-possible-race-in-update_prog_stats-for-32b.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit eabebec0918b4cf32f988086be213f965a63f822
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Tue Oct 26 14:41:32 2021 -0700
bpf: Fixes possible race in update_prog_stats() for 32bit arches
[ Upstream commit d979617aa84d96acca44c2f5778892b4565e322f ]
It seems update_prog_stats() suffers from same issue fixed
in the prior patch:
As it can run while interrupts are enabled, it could
be re-entered and the u64_stats syncp could be mangled.
Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20211026214133.3114279-3-eric.dumazet@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 28a3630c48ee1..9587e5ebddaa3 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -579,11 +579,13 @@ static void notrace update_prog_stats(struct bpf_prog *prog,
* Hence check that 'start' is valid.
*/
start > NO_START_TIME) {
+ unsigned long flags;
+
stats = this_cpu_ptr(prog->stats);
- u64_stats_update_begin(&stats->syncp);
+ flags = u64_stats_update_begin_irqsave(&stats->syncp);
stats->cnt++;
stats->nsecs += sched_clock() - start;
- u64_stats_update_end(&stats->syncp);
+ u64_stats_update_end_irqrestore(&stats->syncp, flags);
}
}
