[FFmpeg-devel] [PATCH v3] avcodec/hevc_ps: fix the problem of memcmp losing effectiveness
tong1.wu at intel.com
tong1.wu at intel.com
Fri Mar 29 17:31:20 EET 2024
From: Tong Wu <tong1.wu at intel.com>
HEVCHdrParams* receives a pointer which points to a dynamically
allocated memory block. It causes the memcmp always returning 1.
Add a function to do the comparision. A condition is also added to
avoid malloc(0).
Reviewed-by: James Almer <jamrial at gmail.com>
Signed-off-by: Tong Wu <tong1.wu at intel.com>
---
libavcodec/hevc_ps.c | 19 +++++++++++++++----
libavcodec/hevc_ps.h | 4 +++-
2 files changed, 18 insertions(+), 5 deletions(-)
diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c
index cbef3ef4cd..6475d86d7d 100644
--- a/libavcodec/hevc_ps.c
+++ b/libavcodec/hevc_ps.c
@@ -449,6 +449,15 @@ static void uninit_vps(FFRefStructOpaque opaque, void *obj)
av_freep(&vps->hdr);
}
+static int compare_vps(const HEVCVPS *vps1, const HEVCVPS *vps2)
+{
+ if (!memcmp(vps1, vps2, offsetof(HEVCVPS, hdr)))
+ return !vps1->vps_num_hrd_parameters ||
+ !memcmp(vps1->hdr, vps2->hdr, vps1->vps_num_hrd_parameters * sizeof(*vps1->hdr));
+
+ return 0;
+}
+
int ff_hevc_decode_nal_vps(GetBitContext *gb, AVCodecContext *avctx,
HEVCParamSets *ps)
{
@@ -545,9 +554,11 @@ int ff_hevc_decode_nal_vps(GetBitContext *gb, AVCodecContext *avctx,
goto err;
}
- vps->hdr = av_calloc(vps->vps_num_hrd_parameters, sizeof(*vps->hdr));
- if (!vps->hdr)
- goto err;
+ if (vps->vps_num_hrd_parameters) {
+ vps->hdr = av_calloc(vps->vps_num_hrd_parameters, sizeof(*vps->hdr));
+ if (!vps->hdr)
+ goto err;
+ }
for (i = 0; i < vps->vps_num_hrd_parameters; i++) {
int common_inf_present = 1;
@@ -569,7 +580,7 @@ int ff_hevc_decode_nal_vps(GetBitContext *gb, AVCodecContext *avctx,
}
if (ps->vps_list[vps_id] &&
- !memcmp(ps->vps_list[vps_id], vps, sizeof(*vps))) {
+ compare_vps(ps->vps_list[vps_id], vps)) {
ff_refstruct_unref(&vps);
} else {
remove_vps(ps, vps_id);
diff --git a/libavcodec/hevc_ps.h b/libavcodec/hevc_ps.h
index cc75aeb8d3..0d8eaf2b3e 100644
--- a/libavcodec/hevc_ps.h
+++ b/libavcodec/hevc_ps.h
@@ -153,7 +153,6 @@ typedef struct PTL {
typedef struct HEVCVPS {
unsigned int vps_id;
- HEVCHdrParams *hdr;
uint8_t vps_temporal_id_nesting_flag;
int vps_max_layers;
@@ -175,6 +174,9 @@ typedef struct HEVCVPS {
uint8_t data[4096];
int data_size;
+ /* Put this at the end of the structure to make it easier to calculate the
+ * size before this pointer, which is used for memcmp */
+ HEVCHdrParams *hdr;
} HEVCVPS;
typedef struct ScalingList {
--
2.41.0.windows.1
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