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authorHe Fengqing <hefengqing@huawei.com>2022-01-22 10:29:36 +0000
committerAlexei Starovoitov <ast@kernel.org>2022-01-25 17:50:03 -0800
commit0e3135d3bfa5dfb658145238d2bc723a8e30c3a3 (patch)
tree3677f5921a1e98e432e54135287577bcc37d8c87
parent63ee956f69d8c181e5251c7ce58b84c1edec0f6a (diff)
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>
-rw-r--r--kernel/bpf/trampoline.c5
1 files changed, 3 insertions, 2 deletions
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