Re: LZ4 : fix the data abort issue.

From: Yeon, JeHyeon (Tom)
Date: Thu Mar 12 2015 - 04:29:06 EST

If the part of the compression data are corrupted, or the compression
data is totally fake, the memory access over the limit is possible.

This is the log from my system usning lz4 decompression.
[6502]data abort, halting
[6503]r0 0x00000000 r1 0x00000000 r2 0xdcea0ffc r3 0xdcea0ffc
[6509]r4 0xb9ab0bfd r5 0xdcea0ffc r6 0xdcea0ff8 r7 0xdce80000
[6515]r8 0x00000000 r9 0x00000000 r10 0x00000000 r11 0xb9a98000
[6522]r12 0xdcea1000 usp 0x00000000 ulr 0x00000000 pc 0x820149bc
[6528]spsr 0x400001f3
and the memory addresses of some variables at the moment are
ref:0xdcea0ffc, op:0xdcea0ffc, oend:0xdcea1000

As you can see, COPYLENGH is 8bytes, so @ref and @op can access the momory
over @oend.

Signed-off-by: tom.yeon <tom.yeon@xxxxxxxxxxxxx>
lib/lz4/lz4_decompress.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c
index 7a85967..f0f5c5c 100644
--- a/lib/lz4/lz4_decompress.c
+++ b/lib/lz4/lz4_decompress.c
@@ -139,6 +139,9 @@ static int lz4_uncompress(const char *source, char *dest, int osize)
/* Error: request to write beyond destination buffer */
if (cpy > oend)
goto _output_error;
+ if ((ref + COPYLENGTH) > oend ||
+ (op + COPYLENGTH) > oend)
+ goto _output_error;
LZ4_SECURECOPY(ref, op, (oend - COPYLENGTH));
while (op < cpy)
*op++ = *ref++;
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