From: Leo Yan leo.yan@linaro.org
[ Upstream commit 197eecb6ecae0b04bd694432f640ff75597fed9c ]
When peeking an event, it has a short path and a long path. The short path uses the session pointer "one_mmap_addr" to directly fetch the event; and the long path needs to read out the event header and the following event data from file and fill into the buffer pointer passed through the argument "buf".
The issue is in the long path that it copies the event header and event data into the same destination address which pointer "buf", this means the event header is overwritten. We are just lucky to run into the short path in most cases, so we don't hit the issue in the long path.
This patch adds the offset "hdr_sz" to the pointer "buf" when copying the event data, so that it can reserve the event header which can be used properly by its caller.
Fixes: 5a52f33adf02 ("perf session: Add perf_session__peek_event()") Signed-off-by: Leo Yan leo.yan@linaro.org Acked-by: Adrian Hunter adrian.hunter@intel.com Acked-by: Jiri Olsa jolsa@redhat.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Kan Liang kan.liang@linux.intel.com Cc: Mark Rutland mark.rutland@arm.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Link: http://lore.kernel.org/lkml/20210605052957.1070720-1-leo.yan@linaro.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/session.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index 56f3039fe2a7..8ff2c98e9032 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -1631,6 +1631,7 @@ int perf_session__peek_event(struct perf_session *session, off_t file_offset, if (event->header.size < hdr_sz || event->header.size > buf_sz) return -1;
+ buf += hdr_sz; rest = event->header.size - hdr_sz;
if (readn(fd, buf, rest) != (ssize_t)rest)