perf session: Validate HEADER_ATTR attr.size before swapping

perf session: Validate HEADER_ATTR attr.size before swapping

Harden PERF_RECORD_HEADER_ATTR handling against crafted perf.data:

- Validate attr.size: must be >= PERF_ATTR_SIZE_VER0, a multiple
  of sizeof(u64), and fit within the event payload.
- Copy only min(attr.size, sizeof(struct perf_event_attr)) bytes
  into a local attr, zeroing the rest so legacy files don't leak
  adjacent event data into new fields.
- Keep the original attr.size so perf_event__synthesize_attr()
  uses it for both allocation and ID-array placement.

Fix perf_event__synthesize_attr() to use attr->size (not the
compiled sizeof) for event allocation and layout, so perf inject
correctly re-synthesizes attrs from files recorded by a different
perf version.  Without this, the ID array destination pointer
(computed via perf_record_header_attr_id()) would be inconsistent
with the allocation when attr->size differs from sizeof.

Also fix the parse-no-sample-id-all test to set attr.size, which
is now validated, and improve error handling in read_attr() for
short reads and invalid attr sizes.

Handle ABI0 pipe/inject events where attr.size is 0: use a local
attr_size variable set to PERF_ATTR_SIZE_VER0 for both the bounded
copy and ID array position, instead of writing back to the event.
Native-endian files may be MAP_SHARED (read-only mmap), so writing
to the event buffer would SIGSEGV.  The swap path handles ABI0 in
perf_event__attr_swap() which writes to the MAP_PRIVATE copy.

header.size alignment is now validated centrally in
perf_session__process_event() (see "Add minimum event size and
alignment validation").

Reported-by: sashiko-bot@kernel.org # Running on a local machine
Reviewed-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.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>