[PATCH] media: iris: Fix out-of-bounds read in timestamp metadata fallback

[Vishnu Reddy <busanna.reddy@oss.qualcomm.com>]

inst->tss[] has VIDEO_MAX_FRAME (32) entries, so valid indexes are 0
through 31. iris_set_ts_metadata() writes at metadata_idx and then
increments it. After the 32nd input buffer, metadata_idx is 32 until
the next input buffer is queued.

If iris_get_ts_metadata() finds no matching timestamp in that window,
its fallback reads inst->tss[32], one entry past the end of the array.
UBSAN (Undefined Behavior Sanity Checker) reports this as an
array-index-out-of-bounds error.

Use the last written entry, metadata_idx - 1, in the fallback instead.
Fall back to slot 0 if nothing has been written yet. Even if stream off
and stream on happen multiple times on the same session, the fallback
always uses the latest metadata received.

Fixes: 17f2a485ca67 ("media: iris: implement vb2 ops for buf_queue and firmware response")
Cc: stable@vger.kernel.org
Signed-off-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
---
 drivers/media/platform/qcom/iris/iris_buffer.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/qcom/iris/iris_buffer.c b/drivers/media/platform/qcom/iris/iris_buffer.c
index eb8de60c1177f..31cba99a665c1 100644
--- a/drivers/media/platform/qcom/iris/iris_buffer.c
+++ b/drivers/media/platform/qcom/iris/iris_buffer.c
@@ -865,9 +865,11 @@ static void iris_get_ts_metadata(struct iris_inst *inst, u64 timestamp_ns,
 		return;
 	}
 
+	i = inst->metadata_idx ? inst->metadata_idx - 1 : 0;
+
 	vbuf->flags &= ~mask;
-	vbuf->flags |= inst->tss[inst->metadata_idx].flags;
-	vbuf->timecode = inst->tss[inst->metadata_idx].tc;
+	vbuf->flags |= inst->tss[i].flags;
+	vbuf->timecode = inst->tss[i].tc;
 }
 
 int iris_vb2_buffer_done(struct iris_inst *inst, struct iris_buffer *buf)

---
base-commit: 2efb7a11f1aa4d2dc285fe2680cca22cb9f72f64
change-id: 20261013-fix-oob-tss-7d317d612cf0

Best regards,
--  
Vishnu Reddy <busanna.reddy@oss.qualcomm.com>