From: Namhyung Kim Date: Wed, 27 Nov 2024 03:13:31 +0000 (-0800) Subject: perf tools: Fix build-id event recording X-Git-Tag: v6.13-rc3~34^2~20 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=23c44f6c83257923b179461694edcf62749bedd5;p=thirdparty%2Fkernel%2Flinux.git perf tools: Fix build-id event recording The build-id events written at the end of the record session are broken due to unexpected data. The write_buildid() writes the fixed length event first and then variable length filename. But a recent change made it write more data in the padding area accidentally. So readers of the event see zero-filled data for the next entry and treat it incorrectly. This resulted in wrong kernel symbols because the kernel DSO loaded a random vmlinux image in the path as it didn't have a valid build-id. Fixes: ae39ba16554e ("perf inject: Fix build ID injection") Reported-by: Linus Torvalds Tested-by: Arnaldo Carvalho de Melo Reviewed-by: Ian Rogers Link: https://lore.kernel.org/r/Z0aRFFW9xMh3mqKB@google.com Signed-off-by: Namhyung Kim --- diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c index 8982f68e7230c..e763e8d99a436 100644 --- a/tools/perf/util/build-id.c +++ b/tools/perf/util/build-id.c @@ -277,7 +277,7 @@ static int write_buildid(const char *name, size_t name_len, struct build_id *bid struct perf_record_header_build_id b; size_t len; - len = sizeof(b) + name_len + 1; + len = name_len + 1; len = PERF_ALIGN(len, sizeof(u64)); memset(&b, 0, sizeof(b)); @@ -286,7 +286,7 @@ static int write_buildid(const char *name, size_t name_len, struct build_id *bid misc |= PERF_RECORD_MISC_BUILD_ID_SIZE; b.pid = pid; b.header.misc = misc; - b.header.size = len; + b.header.size = sizeof(b) + len; err = do_write(fd, &b, sizeof(b)); if (err < 0)