perf header: Validate f_attr.ids section before use in perf_session__read_header()

Browse source

perf_session__read_header() reads f_attr.ids.size from the perf.data
file and divides it by sizeof(u64) to compute nr_ids, which is
declared as int.  No validation is performed on the value before it
is used to allocate arrays and drive a read loop.

On 32-bit architectures, a crafted f_attr.ids.size of 0x100000000
(4 GB) produces nr_ids = 0x20000000, but the allocation size
1 * 0x20000000 * 8 overflows size_t to 0, so zalloc(0) returns a
valid pointer.  The subsequent loop writes 0x20000000 IDs into that
zero-length buffer, corrupting the heap.

On 64-bit, the u64-to-int truncation silently drops high bits,
processing fewer IDs than the file claims.  While not exploitable,
this is a data integrity issue.

Add validation before using f_attr.ids:

- Cap nr_attrs (attrs.size / attr_size) to MAX_NR_ATTRS (1 << 16)
  with overflow-safe u64 comparison before assigning to int
- Reject ids.size not aligned to sizeof(u64)
- Cap ids.size / sizeof(u64) to MAX_IDS_PER_ATTR (1 << 24) to
  prevent int truncation and size_t overflow on 32-bit
- Reject ids sections that extend past the end of the file,
  guarded by S_ISREG() so non-regular files (block devices,
  pipes) are not falsely rejected

Also fix perf_header__getbuffer64() to set errno = EIO when
readn() returns 0 (EOF).  Without this, the out_errno path in
perf_session__read_header() returns -errno which is 0 (success)
on truncated files, causing downstream NULL dereferences.

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>
Assisted-by: Claude:claude-opus-4.6-1m
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

...

This commit is contained in:

Arnaldo Carvalho de Melo 2026-05-02 14:28:06 -03:00

parent 7d19f2008a

commit 7685cc0f2e

1 changed files with 76 additions and 1 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

77

tools/perf/util/header.c

View file