[FFmpeg-devel] [PATCH] avcodec/motion_est: don't add offsets to NULL pointers

[FFmpeg-devel] [PATCH] avcodec/motion_est: don't add offsets to NULL pointers

[James Almer]

Fixes: libavcodec/motion_est.c:94:31: runtime error: applying zero offset to null pointer
Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavcodec/motion_est.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavcodec/motion_est.c b/libavcodec/motion_est.c
index 93be712cc0..bde4591bf7 100644
--- a/libavcodec/motion_est.c
+++ b/libavcodec/motion_est.c
@@ -90,12 +90,14 @@ static inline void init_ref(MotionEstContext *c, uint8_t *const src[3],
         ((y*c->uvstride + x)>>1),
     };
     int i;
-    for(i=0; i<3; i++){
+    for (i = 0; i < 3 && src[i]; i++) {
         c->src[0][i]= src [i] + offset[i];
+    }
+    for (i = 0; i < 3 && ref[i]; i++) {
         c->ref[0][i]= ref [i] + offset[i];
     }
     if(ref_index){
-        for(i=0; i<3; i++){
+        for (i = 0; i < 3 && ref2[i]; i++) {
             c->ref[ref_index][i]= ref2[i] + offset[i];
         }
     }
-- 
2.50.1

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Re: [FFmpeg-devel] [PATCH] avcodec/motion_est: don't add offsets to NULL pointers

[Michael Niedermayer]

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On Sun, Jul 13, 2025 at 08:01:52PM -0300, James Almer wrote:
> Fixes: libavcodec/motion_est.c:94:31: runtime error: applying zero offset to null pointer
> Signed-off-by: James Almer <jamrial@gmail.com>
> ---
>  libavcodec/motion_est.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/libavcodec/motion_est.c b/libavcodec/motion_est.c
> index 93be712cc0..bde4591bf7 100644
> --- a/libavcodec/motion_est.c
> +++ b/libavcodec/motion_est.c
> @@ -90,12 +90,14 @@ static inline void init_ref(MotionEstContext *c, uint8_t *const src[3],
>          ((y*c->uvstride + x)>>1),
>      };
>      int i;
> -    for(i=0; i<3; i++){
> +    for (i = 0; i < 3 && src[i]; i++) {
>          c->src[0][i]= src [i] + offset[i];
> +    }
> +    for (i = 0; i < 3 && ref[i]; i++) {
>          c->ref[0][i]= ref [i] + offset[i];
>      }
>      if(ref_index){
> -        for(i=0; i<3; i++){
> +        for (i = 0; i < 3 && ref2[i]; i++) {
>              c->ref[ref_index][i]= ref2[i] + offset[i];
>          }
>      }

I think the destination should be initialized to NULL
when source is NULL. But i didnt check if it makes a difference,
just from looking at this

thx

[...]

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