From 206204a1162b995e2185275167b22468c00d6b36 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Fri, 20 Jun 2014 22:01:41 -0700 Subject: lz4: ensure length does not wrap Given some pathologically compressed data, lz4 could possibly decide to wrap a few internal variables, causing unknown things to happen. Catch this before the wrapping happens and abort the decompression. Reported-by: "Don A. Bailey" Cc: stable Signed-off-by: Greg Kroah-Hartman --- lib/lz4/lz4_decompress.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'lib/lz4/lz4_decompress.c') diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c index df6839e3ce08..99a03acb7d47 100644 --- a/lib/lz4/lz4_decompress.c +++ b/lib/lz4/lz4_decompress.c @@ -72,6 +72,8 @@ static int lz4_uncompress(const char *source, char *dest, int osize) len = *ip++; for (; len == 255; length += 255) len = *ip++; + if (unlikely(length > (size_t)(length + len))) + goto _output_error; length += len; } -- cgit v1.2.3 From 4148c1f67abf823099b2d7db6851e4aea407f5ee Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Tue, 24 Jun 2014 16:59:01 -0400 Subject: lz4: fix another possible overrun There is one other possible overrun in the lz4 code as implemented by Linux at this point in time (which differs from the upstream lz4 codebase, but will get synced at in a future kernel release.) As pointed out by Don, we also need to check the overflow in the data itself. While we are at it, replace the odd error return value with just a "simple" -1 value as the return value is never used for anything other than a basic "did this work or not" check. Reported-by: "Don A. Bailey" Reported-by: Willy Tarreau Cc: stable Signed-off-by: Greg Kroah-Hartman --- lib/lz4/lz4_decompress.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'lib/lz4/lz4_decompress.c') diff --git a/lib/lz4/lz4_decompress.c b/lib/lz4/lz4_decompress.c index 99a03acb7d47..b74da447e81e 100644 --- a/lib/lz4/lz4_decompress.c +++ b/lib/lz4/lz4_decompress.c @@ -108,6 +108,8 @@ static int lz4_uncompress(const char *source, char *dest, int osize) if (length == ML_MASK) { for (; *ip == 255; length += 255) ip++; + if (unlikely(length > (size_t)(length + *ip))) + goto _output_error; length += *ip++; } @@ -157,7 +159,7 @@ static int lz4_uncompress(const char *source, char *dest, int osize) /* write overflow error detected */ _output_error: - return (int) (-(((char *)ip) - source)); + return -1; } static int lz4_uncompress_unknownoutputsize(const char *source, char *dest, -- cgit v1.2.3 From 4a3a99045177369700c60d074c0e525e8093b0fc Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Thu, 3 Jul 2014 16:06:57 -0700 Subject: 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 --- lib/lz4/lz4_decompress.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'lib/lz4/lz4_decompress.c') 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, -- cgit v1.2.3