From: Greg Kroah-Hartman Date: Thu, 3 Jul 2014 23:06:57 +0000 (-0700) Subject: lz4: add overrun checks to lz4_uncompress_unknownoutputsize() X-Git-Tag: v3.16-rc4~12^2 X-Git-Url: https://git.kernelconcepts.de/?a=commitdiff_plain;h=4a3a99045177369700c60d074c0e525e8093b0fc;p=karo-tx-linux.git lz4: add overrun checks to lz4_uncompress_unknownoutputsize() Jan points out that I forgot to make the needed fixes to the lz4_uncompress_unknownoutputsize() function to mirror the changes done in lz4_decompress() with regards to potential pointer overflows. The only in-kernel user of this function is the zram code, which only takes data from a valid compressed buffer that it made itself, so it's not a big issue. But due to external kernel modules using this function, it's better to be safe here. Reported-by: Jan Beulich Cc: "Don A. Bailey" Cc: stable Signed-off-by: Greg Kroah-Hartman --- diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c index b74da447e81e..7a85967060a5 100644 --- a/lib/lz4/lz4_decompress.c +++ b/lib/lz4/lz4_decompress.c @@ -192,6 +192,8 @@ static int lz4_uncompress_unknownoutputsize(const char *source, char *dest, int s = 255; while ((ip < iend) && (s == 255)) { s = *ip++; + if (unlikely(length > (size_t)(length + s))) + goto _output_error; length += s; } } @@ -232,6 +234,8 @@ static int lz4_uncompress_unknownoutputsize(const char *source, char *dest, if (length == ML_MASK) { while (ip < iend) { int s = *ip++; + if (unlikely(length > (size_t)(length + s))) + goto _output_error; length += s; if (s == 255) continue; @@ -284,7 +288,7 @@ static int lz4_uncompress_unknownoutputsize(const char *source, char *dest, /* write overflow error detected */ _output_error: - return (int) (-(((char *) ip) - source)); + return -1; } int lz4_decompress(const unsigned char *src, size_t *src_len,