From: <gregkh@linuxfoundation.org>
To: hefengqing@huawei.com, ast@kernel.org, john.fastabend@gmail.com
Cc: <stable@vger.kernel.org>
Subject: FAILED: patch "[PATCH] bpf: Fix possible race in inc_misses_counter" failed to apply to 5.15-stable tree
Date: Fri, 04 Feb 2022 09:47:00 +0100 [thread overview]
Message-ID: <164396442065149@kroah.com> (raw)
The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 0e3135d3bfa5dfb658145238d2bc723a8e30c3a3 Mon Sep 17 00:00:00 2001
From: He Fengqing <hefengqing@huawei.com>
Date: Sat, 22 Jan 2022 10:29:36 +0000
Subject: [PATCH] bpf: Fix possible race in inc_misses_counter
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@huawei.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20220122102936.1219518-1-hefengqing@huawei.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 4b6974a195c1..5e7edf913060 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -550,11 +550,12 @@ static __always_inline 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
reply other threads:[~2022-02-04 8:47 UTC|newest]
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