fprobe: Terminate the fgraph_data list when the reservation is not filled

Browse source

fprobe_fgraph_entry() reserves shadow stack space for every fprobe with
an exit handler, but only fills it for those whose entry handler returns
0. fgraph_reserve_data() does not clear the area, so fprobe_return()
parses the unused tail as headers left over from an earlier call, and an
exit handler can run twice or despite its entry handler asking to skip
it.

Write a zero word after the last entry to terminate the walk. A zeroed
slot does not decode to a NULL fprobe on the arches that encode the
header into one unsigned long, since arch_decode_fprobe_header_fp() ORs
in FPROBE_HEADER_MSB_PATTERN, so make read_fprobe_header() return NULL
for a zeroed slot.

Link: https://lore.kernel.org/all/20260917212407.384468-1-devnexen@gmail.com/

Fixes: e0a384434a ("tracing: fprobe: do not zero out unused fgraph_data")
Cc: stable@vger.kernel.org
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

...

This commit is contained in:

David Carlier 2026-09-17 22:24:07 +01:00 • committed by Masami Hiramatsu (Google)

parent d22c3e0088

commit 1d653a1839

1 changed files with 15 additions and 0 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

15

kernel/trace/fprobe.c

View file