[PATCH v2] media: v4l2-ctrls: validate HEVC slice reference lists

[Pengpeng Hou <pengpeng@iscas.ac.cn>]

HEVC slice parameters are shared stateless V4L2 controls, but the common
control validation path currently does not verify the active reference
counts or the ref_idx_l0/ref_idx_l1 entries before driver-specific code
uses them to index fixed 16-entry DPB arrays.

The original report was triggered by Cedrus, but the missing validation
is not Cedrus-specific. Move the bounds checks into the common HEVC slice
control validation path so every stateless HEVC driver gets the same
basic guarantees as soon as the control is queued.

Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
v2:
- move the validation from Cedrus-specific try_ctrl() into
  drivers/media/v4l2-core/v4l2-ctrls-core.c
- keep the checks limited to HEVC slice reference counts and indices

 drivers/media/v4l2-core/v4l2-ctrls-core.c | 24 +++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-ctrls-core.c b/drivers/media/v4l2-core/v4l2-ctrls-core.c
index 6b375720e395..4e7563c8bf4a 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls-core.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls-core.c
@@ -1260,6 +1260,30 @@ static int std_validate_compound(const struct v4l2_ctrl *ctrl, u32 idx,
 		break;
 
 	case V4L2_CTRL_TYPE_HEVC_SLICE_PARAMS:
+		p_hevc_slice_params = p;
+
+		if (p_hevc_slice_params->num_ref_idx_l0_active_minus1 >=
+		    V4L2_HEVC_DPB_ENTRIES_NUM_MAX)
+			return -EINVAL;
+
+		for (i = 0; i <= p_hevc_slice_params->num_ref_idx_l0_active_minus1;
+		     i++)
+			if (p_hevc_slice_params->ref_idx_l0[i] >=
+			    V4L2_HEVC_DPB_ENTRIES_NUM_MAX)
+				return -EINVAL;
+
+		if (p_hevc_slice_params->slice_type != V4L2_HEVC_SLICE_TYPE_B)
+			break;
+
+		if (p_hevc_slice_params->num_ref_idx_l1_active_minus1 >=
+		    V4L2_HEVC_DPB_ENTRIES_NUM_MAX)
+			return -EINVAL;
+
+		for (i = 0; i <= p_hevc_slice_params->num_ref_idx_l1_active_minus1;
+		     i++)
+			if (p_hevc_slice_params->ref_idx_l1[i] >=
+			    V4L2_HEVC_DPB_ENTRIES_NUM_MAX)
+				return -EINVAL;
 		break;
 
 	case V4L2_CTRL_TYPE_HEVC_EXT_SPS_ST_RPS:
-- 
2.50.1 (Apple Git-155)