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avfilter/formats: Make check for buffer overflow redundant

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and remove the redundant check.

This check for whether the allocated buffer is sufficient has been added
in commit 1cbf7fb434 (merging commit
5775a1832c). It is not sufficient to
detect invalid input lists (namely lists with duplicates); its only use
is to avoid buffer overflows. And this can be achieved by simpler means:
Make sure that one allocates space for so many elements as the outer loop
ranges over and break out of the inner loop if a match has been found.
For valid input without duplicates, no further match will be found anyway.

This change will temporarily make the allocated formats array larger
than before and larger than necessary; this will be fixed in a later
commit that avoids the allocation altogether.

If a check for duplicates in the lists is deemed necessary, it should be
done properly somewhere else.

Finally, the error message that is removed in this commit used
__FUNCTION__, which is a GCC extension (C99 added __func__ for this).
So this commit removes a warning when compiling in -pedantic mode.

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt
2020-08-13 18:31:04 +02:00
parent 3a0f080ffa
commit 55eb24a92f
1 changed files with 2 additions and 7 deletions
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9
libavfilter/formats.c
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@@ -65,7 +65,7 @@ do { \
*/ */
#define MERGE_FORMATS(ret, a, b, fmts, nb, type, fail) \ #define MERGE_FORMATS(ret, a, b, fmts, nb, type, fail) \
do { \ do { \
int i, j, k = 0, count = FFMIN(a->nb, b->nb); \ int i, j, k = 0, count = a->nb; \
type ***tmp; \ type ***tmp; \
\ \
if (!(ret = av_mallocz(sizeof(*ret)))) \ if (!(ret = av_mallocz(sizeof(*ret)))) \
@@ -77,13 +77,8 @@ do {
for (i = 0; i < a->nb; i++) \ for (i = 0; i < a->nb; i++) \
for (j = 0; j < b->nb; j++) \ for (j = 0; j < b->nb; j++) \
if (a->fmts[i] == b->fmts[j]) { \ if (a->fmts[i] == b->fmts[j]) { \
if(k >= FFMIN(a->nb, b->nb)){ \
av_log(NULL, AV_LOG_ERROR, "Duplicate formats in %s detected\n", __FUNCTION__); \
av_free(ret->fmts); \
av_free(ret); \
return NULL; \
} \
ret->fmts[k++] = a->fmts[i]; \ ret->fmts[k++] = a->fmts[i]; \
break; \
} \ } \
} \ } \
ret->nb = k; \ ret->nb = k; \