This is a note to let you know that I've just added the patch titled bpf: Fix possible race in inc_misses_counter to the 5.15-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-fix-possible-race-in-inc_misses_counter.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 9a45c44573ba9428f978d99230092ae474f16045 Author: He Fengqing <hefengqing@xxxxxxxxxx> Date: Sat Jan 22 10:29:36 2022 +0000 bpf: Fix possible race in inc_misses_counter [ Upstream commit 0e3135d3bfa5dfb658145238d2bc723a8e30c3a3 ] It seems inc_misses_counter() suffers from same issue fixed in the commit d979617aa84d ("bpf: Fixes possible race in update_prog_stats() for 32bit arches"): As it can run while interrupts are enabled, it could be re-entered and the u64_stats syncp could be mangled. Fixes: 9ed9e9ba2337 ("bpf: Count the number of times recursion was prevented") Signed-off-by: He Fengqing <hefengqing@xxxxxxxxxx> Acked-by: John Fastabend <john.fastabend@xxxxxxxxx> Link: https://lore.kernel.org/r/20220122102936.1219518-1-hefengqing@xxxxxxxxxx Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 6933a9bfee637..2660fbced9ad4 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -541,11 +541,12 @@ static u64 notrace bpf_prog_start_time(void) static void notrace inc_misses_counter(struct bpf_prog *prog) { struct bpf_prog_stats *stats; + unsigned int flags; stats = this_cpu_ptr(prog->stats); - u64_stats_update_begin(&stats->syncp); + flags = u64_stats_update_begin_irqsave(&stats->syncp); u64_stats_inc(&stats->misses); - u64_stats_update_end(&stats->syncp); + u64_stats_update_end_irqrestore(&stats->syncp, flags); } /* The logic is similar to bpf_prog_run(), but with an explicit