From: He Fengqing hefengqing@huawei.com
[ 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@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 Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/trampoline.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
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