diff mbox series

[V2,bpf-next,2/3] bpf: fixes possible race in update_prog_stats() for 32bit arches

Message ID 20211026214133.3114279-3-eric.dumazet@gmail.com (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series bpf: use 32bit safe version of u64_stats | expand

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Context Check Description
bpf/vmtest-bpf-next success VM_Test
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-PR success PR summary
netdev/cover_letter success Series has a cover letter
netdev/fixes_present success Fixes tag not required for -next series
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 6 maintainers not CCed: john.fastabend@gmail.com yhs@fb.com songliubraving@fb.com kafai@fb.com kpsingh@kernel.org andrii@kernel.org
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Fixes tag looks correct
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 15 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/header_inline success No static functions without inline keyword in header files
bpf/vmtest-bpf success VM_Test

Commit Message

Eric Dumazet Oct. 26, 2021, 9:41 p.m. UTC 
From: Eric Dumazet <edumazet@google.com>

It seems update_prog_stats() suffers from same issue fixed
in the prior patch:

As it can run while interrupts are enabled, it could
be re-entered and the u64_stats syncp could be mangled.

Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
---
 kernel/bpf/trampoline.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 39eaaff81953da6006702635fd67d08dd4a7daa2..e5963de368ed34874414d097bc6614ff7e168dd3 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -586,11 +586,13 @@  static void notrace update_prog_stats(struct bpf_prog *prog,
 	     * Hence check that 'start' is valid.
 	     */
 	    start > NO_START_TIME) {
+		unsigned long flags;
+
 		stats = this_cpu_ptr(prog->stats);
-		u64_stats_update_begin(&stats->syncp);
+		flags = u64_stats_update_begin_irqsave(&stats->syncp);
 		stats->cnt++;
 		stats->nsecs += sched_clock() - start;
-		u64_stats_update_end(&stats->syncp);
+		u64_stats_update_end_irqrestore(&stats->syncp, flags);
 	}
 }