[FFmpeg-devel] [PATCH] avcodec/vvcdec: allocate and store structs on their own within the table list

[FFmpeg-devel] [PATCH] avcodec/vvcdec: allocate and store structs on their own within the table list

[James Almer]

Fixes "runtime error: member access within misaligned address 0xf00 for type
'struct bar', which requires # byte alignment" errors under GCC ubsan.

Signed-off-by: James Almer <jamrial@gmail.com>
---
 libavcodec/vvc/vvcdec.c | 34 +++++++++++-----------------------
 1 file changed, 11 insertions(+), 23 deletions(-)

diff --git a/libavcodec/vvc/vvcdec.c b/libavcodec/vvc/vvcdec.c
index 54ada28124..540a05f8cf 100644
--- a/libavcodec/vvc/vvcdec.c
+++ b/libavcodec/vvc/vvcdec.c
@@ -55,14 +55,6 @@ typedef struct TabList {
     l->nb_tabs++;                                        \
 } while (0)
 
-static size_t tl_size(const TabList *l)
-{
-    size_t total = 0;
-    for (int i = 0; i < l->nb_tabs; i++)
-        total += l->tabs[i].size;
-    return total;
-}
-
 static void tl_init(TabList *l, const int zero, const int realloc)
 {
     l->nb_tabs = 0;
@@ -72,32 +64,28 @@ static void tl_init(TabList *l, const int zero, const int realloc)
 
 static int tl_free(TabList *l)
 {
-    for (int i = 1; i < l->nb_tabs; i++) {
-        void **p = l->tabs[i].tab;
-        *p = NULL;
-    }
-    av_freep(l->tabs[0].tab);
+    for (int i = 0; i < l->nb_tabs; i++)
+        av_freep(l->tabs[i].tab);
+
     return 0;
 }
 
 static int tl_create(TabList *l)
 {
-    size_t size = tl_size(l);
     if (l->realloc) {
-        uint8_t *p = l->zero ? av_mallocz(size) : av_malloc(size);
-        if (!p)
-            return AVERROR(ENOMEM);
         tl_free(l);
 
-        // set pointer for each table
         for (int i = 0; i < l->nb_tabs; i++) {
             Tab *t = l->tabs + i;
-            *t->tab = p;
-            p += t->size;
+            *t->tab = l->zero ? av_mallocz(t->size) : av_malloc(t->size);
+            if (!*t->tab)
+                return AVERROR(ENOMEM);
+        }
+    } else if (l->zero) {
+        for (int i = 0; i < l->nb_tabs; i++) {
+            Tab *t = l->tabs + i;
+            memset(*t->tab, 0, t->size);
         }
-    } else {
-        if (l->zero)
-            memset(*l->tabs[0].tab, 0, size);
     }
     return 0;
 }
-- 
2.43.0

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Re: [FFmpeg-devel] [PATCH] avcodec/vvcdec: allocate and store structs on their own within the table list

[Nuo Mi]

On Thu, Jan 18, 2024 at 11:10 PM James Almer <jamrial@gmail.com> wrote:

> Fixes "runtime error: member access within misaligned address 0xf00 for
> type
> 'struct bar', which requires # byte alignment" errors under GCC ubsan.
>

LGTM

Thank you, James

>
> Signed-off-by: James Almer <jamrial@gmail.com>
> ---
>  libavcodec/vvc/vvcdec.c | 34 +++++++++++-----------------------
>  1 file changed, 11 insertions(+), 23 deletions(-)
>
> diff --git a/libavcodec/vvc/vvcdec.c b/libavcodec/vvc/vvcdec.c
> index 54ada28124..540a05f8cf 100644
> --- a/libavcodec/vvc/vvcdec.c
> +++ b/libavcodec/vvc/vvcdec.c
> @@ -55,14 +55,6 @@ typedef struct TabList {
>      l->nb_tabs++;                                        \
>  } while (0)
>
> -static size_t tl_size(const TabList *l)
> -{
> -    size_t total = 0;
> -    for (int i = 0; i < l->nb_tabs; i++)
> -        total += l->tabs[i].size;
> -    return total;
> -}
> -
>  static void tl_init(TabList *l, const int zero, const int realloc)
>  {
>      l->nb_tabs = 0;
> @@ -72,32 +64,28 @@ static void tl_init(TabList *l, const int zero, const
> int realloc)
>
>  static int tl_free(TabList *l)
>  {
> -    for (int i = 1; i < l->nb_tabs; i++) {
> -        void **p = l->tabs[i].tab;
> -        *p = NULL;
> -    }
> -    av_freep(l->tabs[0].tab);
> +    for (int i = 0; i < l->nb_tabs; i++)
> +        av_freep(l->tabs[i].tab);
> +
>      return 0;
>  }
>
>  static int tl_create(TabList *l)
>  {
> -    size_t size = tl_size(l);
>      if (l->realloc) {
> -        uint8_t *p = l->zero ? av_mallocz(size) : av_malloc(size);
> -        if (!p)
> -            return AVERROR(ENOMEM);
>          tl_free(l);
>
> -        // set pointer for each table
>          for (int i = 0; i < l->nb_tabs; i++) {
>              Tab *t = l->tabs + i;
> -            *t->tab = p;
> -            p += t->size;
> +            *t->tab = l->zero ? av_mallocz(t->size) : av_malloc(t->size);
> +            if (!*t->tab)
> +                return AVERROR(ENOMEM);
> +        }
> +    } else if (l->zero) {
> +        for (int i = 0; i < l->nb_tabs; i++) {
> +            Tab *t = l->tabs + i;
> +            memset(*t->tab, 0, t->size);
>          }
> -    } else {
> -        if (l->zero)
> -            memset(*l->tabs[0].tab, 0, size);
>      }
>      return 0;
>  }
> --
> 2.43.0
>
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>
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