[coreboot] Patch set updated for coreboot: 120bd66 lib: Prevent unaligned memory access and fix endianess in LZMA decode library.

Hung-Te Lin (hungte@chromium.org) gerrit at coreboot.org
Fri Feb 1 05:42:40 CET 2013

Hung-Te Lin (hungte at chromium.org) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/2246


commit 120bd66b5ffbc7ca52a7255191d1c3025c6a2803
Author: Hung-Te Lin <hungte at chromium.org>
Date:   Thu Jan 31 12:14:46 2013 +0800

    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
    To fix this, reconstruct outSize in little-endian way.
    Change-Id: If678e735cb270c3e5e29f36f1fad318096bf7d59
    Signed-off-by: Hung-Te Lin <hungte at chromium.org>
 src/lib/lzma.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/lib/lzma.c b/src/lib/lzma.c
index f0b88c1..7a62b84 100644
--- a/src/lib/lzma.c
+++ b/src/lib/lzma.c
@@ -29,9 +29,15 @@ unsigned long ulzma(unsigned char * src, unsigned char * dst)
 	/* in pre-ram, it must go on the stack */
 	unsigned char scratchpad[15980];
+	unsigned char *cp;
 	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 at LZMACompress: put_64). To prevent accessing by
+	 * unaligned memory access and to load endianess correctly, read each
+	 * byte and re-costruct. */
+	outSize = cp[3] << 24 | cp[2] << 16 | cp[1] << 8 | cp[0];
 	if (LzmaDecodeProperties(&state.Properties, properties, LZMA_PROPERTIES_SIZE) != LZMA_RESULT_OK) {
 		printk(BIOS_WARNING, "lzma: Incorrect stream properties.\n");
 		return 0;

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