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perf header: Use write lock when translating BPF prog info pointers

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write_bpf_prog_info() holds a read lock while temporarily mutating
info_linear via bpil_addr_to_offs()/bpil_offs_to_addr().  Between these
two calls, the pointers in info_linear contain file offsets instead of
heap addresses.  Concurrent readers holding the same read lock see the
file offsets and dereference them as pointers.

Use down_write()/up_write() instead of down_read()/up_read() to exclude
concurrent readers during the addr-to-offset-to-addr translation window.

Fixes: 63ac7968a1fb ("perf bpf: Save bpf_prog_info information as headers to perf.data")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
This commit is contained in:
Arnaldo Carvalho de Melo
2026-08-02 11:27:10 -03:00
committed by Namhyung Kim
parent 01765b456f
commit 60f2f5b765
1 changed files with 3 additions and 2 deletions
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5
tools/perf/util/header.c
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@@ -1120,7 +1120,8 @@ static int write_bpf_prog_info(struct feat_fd *ff __maybe_unused,
struct rb_node *next;
int ret = 0;
down_read(&env->bpf_progs.lock);
/* write lock: bpil_addr_to_offs() temporarily mutates info_linear */
down_write(&env->bpf_progs.lock);
ret = do_write(ff, &env->bpf_progs.infos_cnt,
sizeof(env->bpf_progs.infos_cnt));
@@ -1150,7 +1151,7 @@ static int write_bpf_prog_info(struct feat_fd *ff __maybe_unused,
goto out;
}
out:
up_read(&env->bpf_progs.lock);
up_write(&env->bpf_progs.lock);
return ret;
#else
pr_err("ERROR: Trying to write bpf_prog_info without libbpf support.\n");