Messages in this thread | | | Date | Tue, 8 Jun 2021 13:07:22 +0200 | From | Jiri Olsa <> | Subject | Re: [PATCH] perf session: Correct buffer copying when peek event |
| |
On Sat, Jun 05, 2021 at 01:29:57PM +0800, Leo Yan wrote: > When peek an event, it has a short path and a long path. The short path > uses the session pointer "one_mmap_addr" to directly fetch event; and > the long path needs to read out the event header and the followed 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> > --- > 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 106b3d60881a..e59242c361ce 100644 > --- a/tools/perf/util/session.c > +++ b/tools/perf/util/session.c > @@ -1723,6 +1723,7 @@ 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;
nice ;-)
Acked-by: Jiri Olsa <jolsa@redhat.com>
thanks, jirka
> rest = event->header.size - hdr_sz; > > if (readn(fd, buf, rest) != (ssize_t)rest) > -- > 2.25.1 >
| |