From 780f1005c8e5513098f8f677bebc735107824920 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 3 Jul 2014 16:06:57 -0700 Subject: [PATCH] lz4: add overrun checks to lz4_uncompress_unknownoutputsize() commit 4a3a99045177369700c60d074c0e525e8093b0fc upstream. 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" Signed-off-by: Greg Kroah-Hartman --- lib/lz4/lz4_decompress.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c index b74da44..7a85967 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, -- 2.7.4