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| author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2026-05-02 14:37:39 -0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2026-05-29 11:44:34 -0300 |
| commit | 4b90eb4237f37820762af837a0374622eeb498f0 (patch) | |
| tree | a4b77af7c17169e137a0d11b501fdbccd29f566d /tools | |
| parent | 57dfceb203c34d16e209061a34c75e1856dc08b5 (diff) | |
| download | linux-next-history-4b90eb4237f37820762af837a0374622eeb498f0.tar.gz | |
perf header: Sanity check HEADER_EVENT_DESC attr.size before swap
read_event_desc() reads nre (event count), sz (attr size), and nr
(IDs per event) from the file and uses them to control allocations
and loops without validating them against the section size.
A crafted perf.data could trigger large allocations or many loop
iterations before __do_read() eventually rejects the reads.
Add bounds checks in read_event_desc():
- Reject sz smaller than PERF_ATTR_SIZE_VER0.
- Require at least one event (nre > 0).
- Check that nre events fit in the remaining section, using the
minimum per-event footprint of sz + sizeof(u32).
- Pre-swap attr->size to native byte order, then reject values
below PERF_ATTR_SIZE_VER0 or above sz before calling
perf_event__attr_swap() to prevent heap out-of-bounds access.
- Handle ABI0 (attr.size == 0): substitute PERF_ATTR_SIZE_VER0,
and on native-endian files write the value back so
free_event_desc() does not treat the zero as its end-of-array
sentinel (it iterates while attr.size != 0). The swap path
skips the write-back — perf_event__attr_swap() has its own
ABI0 fallback that sets VER0 after swapping.
- Check that nr IDs fit in the remaining section before allocating.
Fixes: b30b61729246 ("perf tools: Fix a problem when opening old perf.data with different byte order")
Reported-by: sashiko-bot@kernel.org # Running on a local machine
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Assisted-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/perf/util/header.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c index 90417a478c8db..37d7c9849e0e9 100644 --- a/tools/perf/util/header.c +++ b/tools/perf/util/header.c @@ -2173,9 +2173,28 @@ static struct evsel *read_event_desc(struct feat_fd *ff) if (do_read_u32(ff, &nre)) goto error; + /* Size of each of the nre attributes. */ if (do_read_u32(ff, &sz)) goto error; + /* + * Require at least one event with an attr no smaller than the + * first published struct, and reject sz values where + * sz + sizeof(u32) would overflow size_t (possible on 32-bit) + * or nre == UINT32_MAX where nre + 1 wraps to 0 in the calloc. + * + * The minimum section footprint per event is sz bytes for the + * attr plus a u32 for the id count, check that nre events fit. + */ + if (!nre || sz < PERF_ATTR_SIZE_VER0 || + sz > ff->size || (size_t)sz > SIZE_MAX - sizeof(u32) || + nre == UINT32_MAX || + nre > (ff->size - ff->offset) / (sz + sizeof(u32))) { + pr_err("Invalid HEADER_EVENT_DESC: nre=%u sz=%u (min %d)\n", + nre, sz, PERF_ATTR_SIZE_VER0); + goto error; + } + /* buffer to hold on file attr struct */ buf = malloc(sz); if (!buf) @@ -2191,6 +2210,9 @@ static struct evsel *read_event_desc(struct feat_fd *ff) msz = sz; for (i = 0, evsel = events; i < nre; evsel++, i++) { + struct perf_event_attr *attr = buf; + u32 attr_size; + evsel->core.idx = i; /* @@ -2200,6 +2222,32 @@ static struct evsel *read_event_desc(struct feat_fd *ff) if (__do_read(ff, buf, sz)) goto error; + /* Reject before attr_swap to prevent OOB via bswap_safe() */ + attr_size = ff->ph->needs_swap ? bswap_32(attr->size) : attr->size; + /* ABI0: size == 0 means the producer didn't set it */ + if (!attr_size) { + attr_size = PERF_ATTR_SIZE_VER0; + /* + * Write back so free_event_desc() doesn't + * treat this event as the end-of-array sentinel + * (it iterates while attr.size != 0). + * + * Only for native — the swap path must NOT + * write native-endian VER0 here because + * perf_event__attr_swap() would re-swap it + * to 0x40000000, defeating bswap_safe() bounds. + * perf_event__attr_swap() has its own ABI0 + * fallback that sets VER0 after swapping. + */ + if (!ff->ph->needs_swap) + attr->size = attr_size; + } + if (attr_size < PERF_ATTR_SIZE_VER0 || attr_size > sz) { + pr_err("Event %d attr.size (%u) invalid (min: %d, max: %u)\n", + i, attr_size, PERF_ATTR_SIZE_VER0, sz); + goto error; + } + if (ff->ph->needs_swap) perf_event__attr_swap(buf); @@ -2221,6 +2269,12 @@ static struct evsel *read_event_desc(struct feat_fd *ff) if (!nr) continue; + /* Prevent oversized allocation from crafted nr */ + if (nr > (ff->size - ff->offset) / sizeof(*id)) { + pr_err("Event %d: id count %u exceeds remaining section\n", i, nr); + goto error; + } + id = calloc(nr, sizeof(*id)); if (!id) goto error; |