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lib: Prevent unaligned memory access and fix endianess in LZMA decode library. 

LZMA decode library used to retrieve output size by:
  outSize = *(UInt32 *)(src + LZMA_PROPERTIES_SIZE);

'src' is aligned but LZMA_PROPERTIES_SIZE may refer to an unaligned address like
src+5, and using that as integer pointer may fail on platforms like ARM. Also
this will fail on systems using big-endian (outSize was encoded in
little-endian).

To fix this, reconstruct outSize in little-endian way.

Change-Id: If678e735cb270c3e5e29f36f1fad318096bf7d59
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/2246
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
This commit is contained in:
Hung-Te Lin 2013-01-31 12:14:46 +08:00 committed by Ronald G. Minnich
parent 05dccae75d
commit d51557ade2
1 changed files with 7 additions and 1 deletions
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8
src/lib/lzma.c
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@ -29,9 +29,15 @@ unsigned long ulzma(unsigned char * src, unsigned char * dst)
#endif #endif
/* in pre-ram, it must go on the stack */ /* in pre-ram, it must go on the stack */
unsigned char scratchpad[15980]; unsigned char scratchpad[15980];
unsigned char *cp;
memcpy(properties, src, LZMA_PROPERTIES_SIZE); memcpy(properties, src, LZMA_PROPERTIES_SIZE);
outSize = *(UInt32 *)(src + LZMA_PROPERTIES_SIZE); /* The outSize in LZMA stream is a 64bit integer stored in little-endian
* (ref: lzma.cc@LZMACompress: put_64). To prevent accessing by
* unaligned memory address and to load in correct endianess, read each
* byte and re-costruct. */
cp = src + LZMA_PROPERTIES_SIZE;
outSize = cp[3] << 24 | cp[2] << 16 | cp[1] << 8 | cp[0];
if (LzmaDecodeProperties(&state.Properties, properties, LZMA_PROPERTIES_SIZE) != LZMA_RESULT_OK) { if (LzmaDecodeProperties(&state.Properties, properties, LZMA_PROPERTIES_SIZE) != LZMA_RESULT_OK) {
printk(BIOS_WARNING, "lzma: Incorrect stream properties.\n"); printk(BIOS_WARNING, "lzma: Incorrect stream properties.\n");
return 0; return 0;