2024-02-29 07:12:36

by Ian Rogers

Subject: [PATCH v1] libperf evlist: Avoid out-of-bounds access

Parallel testing appears to show a race between allocating and setting
evsel ids. As there is a bounds check on the xyarray it yields a segv
like:

```
AddressSanitizer:DEADLYSIGNAL

=================================================================

==484408==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000010

==484408==The signal is caused by a WRITE memory access.

==484408==Hint: address points to the zero page.

#0 0x55cef5d4eff4 in perf_evlist__id_hash tools/lib/perf/evlist.c:256
#1 0x55cef5d4f132 in perf_evlist__id_add tools/lib/perf/evlist.c:274
#2 0x55cef5d4f545 in perf_evlist__id_add_fd tools/lib/perf/evlist.c:315
#3 0x55cef5a1923f in store_evsel_ids util/evsel.c:3130
#4 0x55cef5a19400 in evsel__store_ids util/evsel.c:3147
#5 0x55cef5888204 in __run_perf_stat tools/perf/builtin-stat.c:832
#6 0x55cef5888c06 in run_perf_stat tools/perf/builtin-stat.c:960
#7 0x55cef58932db in cmd_stat tools/perf/builtin-stat.c:2878
..
```

Avoid this crash by early exiting the perf_evlist__id_add_fd and
perf_evlist__id_add is the access is out-of-bounds.

Signed-off-by: Ian Rogers <[email protected]>
---
tools/lib/perf/evlist.c | 18 ++++++++++++------
tools/lib/perf/include/internal/evlist.h | 4 ++--
2 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
index 058e3ff10f9b..c6d67fc9e57e 100644
--- a/tools/lib/perf/evlist.c
+++ b/tools/lib/perf/evlist.c
@@ -248,10 +248,10 @@ u64 perf_evlist__read_format(struct perf_evlist *evlist)

static void perf_evlist__id_hash(struct perf_evlist *evlist,
struct perf_evsel *evsel,
- int cpu, int thread, u64 id)
+ int cpu_map_idx, int thread, u64 id)
{
int hash;
- struct perf_sample_id *sid = SID(evsel, cpu, thread);
+ struct perf_sample_id *sid = SID(evsel, cpu_map_idx, thread);

sid->id = id;
sid->evsel = evsel;
@@ -269,21 +269,27 @@ void perf_evlist__reset_id_hash(struct perf_evlist *evlist)

void perf_evlist__id_add(struct perf_evlist *evlist,
struct perf_evsel *evsel,
- int cpu, int thread, u64 id)
+ int cpu_map_idx, int thread, u64 id)
{
- perf_evlist__id_hash(evlist, evsel, cpu, thread, id);
+ if (!SID(evsel, cpu_map_idx, thread))
+ return;
+
+ perf_evlist__id_hash(evlist, evsel, cpu_map_idx, thread, id);
evsel->id[evsel->ids++] = id;
}

int perf_evlist__id_add_fd(struct perf_evlist *evlist,
struct perf_evsel *evsel,
- int cpu, int thread, int fd)
+ int cpu_map_idx, int thread, int fd)
{
u64 read_data[4] = { 0, };
int id_idx = 1; /* The first entry is the counter value */
u64 id;
int ret;

+ if (!SID(evsel, cpu_map_idx, thread))
+ return -1;
+
ret = ioctl(fd, PERF_EVENT_IOC_ID, &id);
if (!ret)
goto add;
@@ -312,7 +318,7 @@ int perf_evlist__id_add_fd(struct perf_evlist *evlist,
id = read_data[id_idx];

add:
- perf_evlist__id_add(evlist, evsel, cpu, thread, id);
+ perf_evlist__id_add(evlist, evsel, cpu_map_idx, thread, id);
return 0;
}

diff --git a/tools/lib/perf/include/internal/evlist.h b/tools/lib/perf/include/internal/evlist.h
index d86ffe8ed483..f43bdb9b6227 100644
--- a/tools/lib/perf/include/internal/evlist.h
+++ b/tools/lib/perf/include/internal/evlist.h
@@ -126,11 +126,11 @@ u64 perf_evlist__read_format(struct perf_evlist *evlist);

void perf_evlist__id_add(struct perf_evlist *evlist,
struct perf_evsel *evsel,
- int cpu, int thread, u64 id);
+ int cpu_map_idx, int thread, u64 id);

int perf_evlist__id_add_fd(struct perf_evlist *evlist,
struct perf_evsel *evsel,
- int cpu, int thread, int fd);
+ int cpu_map_idx, int thread, int fd);

void perf_evlist__reset_id_hash(struct perf_evlist *evlist);

--
2.44.0.278.ge034bb2e1d-goog

2024-03-01 19:32:53

by Namhyung Kim

Subject: Re: [PATCH v1] libperf evlist: Avoid out-of-bounds access

On Wed, 28 Feb 2024 23:07:57 -0800, Ian Rogers wrote:
> Parallel testing appears to show a race between allocating and setting
> evsel ids. As there is a bounds check on the xyarray it yields a segv
> like:
>
> ```
> AddressSanitizer:DEADLYSIGNAL
>
> [...]

Applied to perf-tools-next, thanks!

Best regards,
--
Namhyung Kim <[email protected]>