[PATCH 2/5] perf auxtrace: Fix queue grow overflow and old array leak

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

auxtrace_queues__grow() has two bugs:

1. When idx is UINT_MAX, the caller passes new_nr_queues = idx + 1 = 0.
   The function skips growing (since any nr_queues >= 0), returns
   success, and the caller accesses queue_array[UINT_MAX] — an OOB
   heap write.  Fix by rejecting new_nr_queues == 0 up front.

2. The function allocates a new queue_array via calloc and copies
   elements from the old array, but never frees the old array.  Fix
   by saving the old pointer and freeing it after the copy.

Fixes: e502789302a6ece9 ("perf auxtrace: Add helpers for queuing AUX area tracing data")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/auxtrace.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index 0b851f32e98c8517..aa749e1c30365a02 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -251,8 +251,12 @@ static int auxtrace_queues__grow(struct auxtrace_queues *queues,
 {
 	unsigned int nr_queues = queues->nr_queues;
 	struct auxtrace_queue *queue_array;
+	struct auxtrace_queue *old_array = queues->queue_array;
 	unsigned int i;
 
+	if (!new_nr_queues)
+		return -EINVAL;
+
 	if (!nr_queues)
 		nr_queues = AUXTRACE_INIT_NR_QUEUES;
 
@@ -267,16 +271,17 @@ static int auxtrace_queues__grow(struct auxtrace_queues *queues,
 		return -ENOMEM;
 
 	for (i = 0; i < queues->nr_queues; i++) {
-		list_splice_tail(&queues->queue_array[i].head,
+		list_splice_tail(&old_array[i].head,
 				 &queue_array[i].head);
-		queue_array[i].tid = queues->queue_array[i].tid;
-		queue_array[i].cpu = queues->queue_array[i].cpu;
-		queue_array[i].set = queues->queue_array[i].set;
-		queue_array[i].priv = queues->queue_array[i].priv;
+		queue_array[i].tid = old_array[i].tid;
+		queue_array[i].cpu = old_array[i].cpu;
+		queue_array[i].set = old_array[i].set;
+		queue_array[i].priv = old_array[i].priv;
 	}
 
 	queues->nr_queues = nr_queues;
 	queues->queue_array = queue_array;
+	free(old_array);
 
 	return 0;
 }
-- 
2.55.0