| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.16 38/43] bpf: Fix possible race in inc_misses_counter | Date | Fri, 4 Feb 2022 10:22:45 +0100 |
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From: He Fengqing <hefengqing@huawei.com>
commit 0e3135d3bfa5dfb658145238d2bc723a8e30c3a3 upstream.
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- kernel/bpf/trampoline.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -542,11 +542,12 @@ static __always_inline u64 notrace bpf_p 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
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