[vlc-devel] [PATCH] block: Fix buffer total size in block_Alloc()
skeletk13 at gmail.com
Thu Apr 26 14:49:00 CEST 2012
The total size of the buffer (i_size) was initialized with the whole
allocated size for the block. This fooled block_Realloc() in the case of
resizing to slightly larger, with the extra size in range from
32 to 32 + 80 bytes. block_Realloc() assumed it had enough space left in
the buffer padding to avoid reallocating memory.
Consequently, the block ended up with a i_buffer field with a value
larger than the allocated memory around p_buffer.
In the end, this could cause memory corruptions in all sorts of cases.
In my case, vlc was crashing while encoutering a corrupted mp3 file.
src/misc/block.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/src/misc/block.c b/src/misc/block.c
index bed781d..bd62b9d 100644
@@ -133,7 +133,7 @@ block_t *block_Alloc (size_t size)
if (unlikely(b == NULL))
- block_Init (b, b + 1, alloc);
+ block_Init (b, b + 1, alloc - sizeof (block_t));
static_assert ((BLOCK_PADDING % BLOCK_ALIGN) == 0,
"BLOCK_PADDING must be a multiple of BLOCK_ALIGN");
b->p_buffer += BLOCK_PADDING + BLOCK_ALIGN - 1;
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