[PATCH 4/9] perf cs-etm: Require full global header in auxtrace_info size check

[Arnaldo Carvalho de Melo]

From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

cs_etm__process_auxtrace_info() checks that header.size covers
event_header_size + INFO_HEADER_SIZE (16 bytes total), but then
accesses ptr[CS_PMU_TYPE_CPUS] at offset 24 from the start of the
event.  A crafted 16-byte auxtrace_info event passes the size check
but reads out-of-bounds.

Include CS_ETM_HEADER_SIZE in the minimum size check so that the
global header entries (version, pmu_type_cpus, snapshot) are
guaranteed to fit within the event.

Fixes: 55c1de9973d66516 ("perf cs-etm: Print auxtrace info even if OpenCSD isn't linked")
Reported-by: sashiko-bot <sashiko-bot@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: James Clark <james.clark@xxxxxxx>
Cc: Leo Yan <leo.yan@xxxxxxxxxx>
Assisted-by: Claude <noreply@xxxxxxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/cs-etm-base.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/cs-etm-base.c b/tools/perf/util/cs-etm-base.c
index 4abe416e3febd2cc..aebef71d3a0a1d7b 100644
--- a/tools/perf/util/cs-etm-base.c
+++ b/tools/perf/util/cs-etm-base.c
@@ -170,7 +170,9 @@ int cs_etm__process_auxtrace_info(union perf_event *event,
 	u64 *ptr = NULL;
 	u64 hdr_version;
 
-	if (auxtrace_info->header.size < (event_header_size + INFO_HEADER_SIZE))
+	/* Ensure priv[] is large enough for the global header entries */
+	if (auxtrace_info->header.size < (event_header_size + INFO_HEADER_SIZE +
+					  CS_ETM_HEADER_SIZE))
 		return -EINVAL;
 
 	/* First the global part */
-- 
2.54.0