diff options
| author | Ian Rogers <irogers@google.com> | 2026-09-29 15:23:32 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-10-01 14:02:06 +0200 |
| commit | b9d1fdc6f4ac1b6e49f9deafaf137da1407d9af1 (patch) | |
| tree | 3136fb2d281dcbcbd878310c6fee5644ac283526 /include/linux | |
| parent | ffb684f2aa141eeb0caa6308422e7e05d1ded7c4 (diff) | |
perf: Replace perf_event_header__init_id with full header init
perf_iterate_sb() invokes its callback for each matching perf_event on
the CPU and task context, passing a shared caller-allocated event
structure.
perf_event_header__init_id() mutated header->size in place by adding
event->id_header_size, requiring sideband output callbacks to save and
restore header fields across iterations. Three sideband callbacks failed
to save and restore header.size around perf_event_header__init_id():
- perf_event_ksymbol_output()
- perf_event_bpf_output()
- perf_event_text_poke_output()
When multiple events with attr.ksymbol, attr.bpf_event, or
attr.text_poke and sample_id_all are active on the same CPU, each
subsequent event receives a record whose header.size is inflated by all
preceding events' id_header_size values while only a single id_sample is
written, leaving uninitialized ring-buffer bytes at the end of the
record and causing userspace perf to fail with -EFAULT ("Bad address")
when parsing the sample_id trailer.
Similarly, perf_event_mmap_output() set PERF_RECORD_MISC_MMAP_BUILD_ID
in mmap_event->event_id.header.misc when event->attr.build_id was
enabled, but only saved and restored header.size and header.type. If an
event with attr.build_id was followed by an event with attr.mmap2 and
!attr.build_id, the second event received PERF_RECORD_MISC_MMAP_BUILD_ID
in header.misc while its payload contained maj/min/ino/ino_generation
instead of a build ID.
Rather than splitting header initialization between callers and output
callbacks and saving/restoring mutated header fields, replace
perf_event_header__init_id() with perf_event_header__init(), which
initializes header->type, header->misc, and header->size alongside the
sample_id fields on each invocation.
Fixes: 76193a94522f ("perf, bpf: Introduce PERF_RECORD_KSYMBOL")
Fixes: 6ee52e2a3fe4 ("perf, bpf: Introduce PERF_RECORD_BPF_EVENT")
Fixes: e17d43b93e54 ("perf: Add perf text poke event")
Fixes: 88a16a130933 ("perf: Add build id data in mmap2 event")
Assisted-by: Antigravity:gemini-3.1-pro
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260929222332.973435-1-irogers@google.com
Cc: stable@vger.kernel.org
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/perf_event.h | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 915c6fd3f084..2d5e7687875b 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1506,9 +1506,10 @@ is_default_overflow_handler(struct perf_event *event) } extern void -perf_event_header__init_id(struct perf_event_header *header, - struct perf_sample_data *data, - struct perf_event *event); +perf_event_header__init(struct perf_event_header *header, + struct perf_sample_data *data, + u32 type, u16 misc, u16 size, + struct perf_event *event); extern void perf_event__output_id_sample(struct perf_event *event, struct perf_output_handle *handle, |