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avcodec/xface: correct the XFACE_MAX_* values 

Fixes out of array access

Fixes: asan_stack-oob_32c12e5_2536_cov_2442316831_lena.xface
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2014-12-16 18:57:54 +01:00
parent 3030fb7e0d
commit 93a5a16f13
1 changed files with 5 additions and 5 deletions
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10
libavcodec/xface.h
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@ -41,17 +41,17 @@
/*
* Image is encoded as a big integer, using characters from '~' to
* '!', for a total of 94 symbols. In order to express
* 48x48*2=8*XFACE_MAX_WORDS=4608
* bits, we need a total of 704 digits, as given by:
* ceil(lg_94(2^4608)) = 704
* 48x48 pixels with the worst case encoding 666 symbols should
* be sufficient.
*/
#define XFACE_MAX_DIGITS 704
#define XFACE_MAX_DIGITS 666
#define XFACE_BITSPERWORD 8
#define XFACE_WORDCARRY (1 << XFACE_BITSPERWORD)
#define XFACE_WORDMASK (XFACE_WORDCARRY - 1)
#define XFACE_MAX_WORDS ((XFACE_PIXELS * 2 + XFACE_BITSPERWORD - 1) / XFACE_BITSPERWORD)
// This must be larger or equal to log256(94^XFACE_MAX_DIGITS)
#define XFACE_MAX_WORDS 546
/* Portable, very large unsigned integer arithmetic is needed.
* Implementation uses arrays of WORDs. */