[PATCH v2] perf: prevent overflow in size calculation

[Cody Schafer]

A large enough symbol size causes an overflow in the size parameter to the
histogram allocation, leading to a segfault in symbol__inc_addr_samples later
on when this histogram is accessed.

In the case of being called via perf-report, this returns back and
gracefully ignores the sample, eventually ignoring the chained return
value of perf_session_deliver_event in flush_sample_queue.

Signed-off-by: Cody Schafer <cody@xxxxxxxxxxxxxxxxxx>
---
 tools/perf/util/annotate.c |   13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 8069dfb..73a1919 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -426,7 +426,18 @@ int symbol__alloc_hist(struct symbol *sym)
 {
 	struct annotation *notes = symbol__annotation(sym);
 	const size_t size = symbol__size(sym);
-	size_t sizeof_sym_hist = (sizeof(struct sym_hist) + size * sizeof(u64));
+	size_t sizeof_sym_hist;
+
+	/* Check for overflow when calculating sizeof_sym_hist */
+	if (size > (SIZE_MAX / sizeof(u64) - sizeof(struct sym_hist)))
+		return -1;
+
+	sizeof_sym_hist = (sizeof(struct sym_hist) + size * sizeof(u64));
+
+	/* Check for overflow in zalloc argument */
+	if (sizeof_sym_hist > (SIZE_MAX / symbol_conf.nr_events
+				- sizeof(*notes->src)))
+		return -1;
 
 	notes->src = zalloc(sizeof(*notes->src) + symbol_conf.nr_events * sizeof_sym_hist);
 	if (notes->src == NULL)
-- 
1.7.9.5

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