Willy Tarreau 39e37e3dd0 lzo: check for length overrun in variable length encoding. ... This fix ensures that we never meet an integer overflow while adding 255 while parsing a variable length encoding. It works differently from commit 206a81c ("lzo: properly check for overruns") because instead of ensuring that we don't overrun the input, which is tricky to guarantee due to many assumptions in the code, it simply checks that the cumulated number of 255 read cannot overflow by bounding this number. The MAX_255_COUNT is the maximum number of times we can add 255 to a base count without overflowing an integer. The multiply will overflow when multiplying 255 by more than MAXINT/255. The sum will overflow earlier depending on the base count. Since the base count is taken from a u8 and a few bits, it is safe to assume that it will always be lower than or equal to 2*255, thus we can always prevent any overflow by accepting two less 255 steps. This patch also reduces the CPU overhead and actually increases performance by 1.1% compared to the initial code, while the previous fix costs 3.1% (measured on x86_64). The fix needs to be backported to all currently supported stable kernels. Reported-by: Willem Pinckaers <willem@lekkertech.net> Cc: "Don A. Bailey" <donb@securitymouse.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> (cherry picked from commit 72cf90124e) Signed-off-by: Willy Tarreau <w@1wt.eu>		2014-11-23 10:55:52 +01:00
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lzo1x_compress.c	lib/lzo: Update LZO compression to current upstream version	2014-11-23 10:55:51 +01:00
lzo1x_decompress.c	lzo: check for length overrun in variable length encoding.	2014-11-23 10:55:52 +01:00
lzodefs.h	lib/lzo: Update LZO compression to current upstream version	2014-11-23 10:55:51 +01:00
Makefile	Add LZO1X algorithm to the kernel	2007-07-10 17:51:13 -07:00