Commit Graph

9 Commits

Author SHA1 Message Date
Phillip Lougher
3689456b4b squashfs: fix use of uninitialised variable in zlib & xz decompressors
Fix potential use of uninitialised variable caused by recent
decompressor code optimisations.

In zlib_uncompress (zlib_wrapper.c) we have

	int zlib_err, zlib_init = 0;
	...
	do {
		...
			if (avail == 0) {
				offset = 0;
				put_bh(bh[k++]);
				continue;
			}
		...
		zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
		...
	} while (zlib_err == Z_OK);

If continue is executed (avail == 0) then the while condition will be
evaluated testing zlib_err, which is uninitialised first time around the
loop.

Fix this by getting rid of the 'if (avail == 0)' condition test, this
edge condition should not be being handled in the decompressor code, and
instead handle it generically in the caller code.

Similarly for xz_wrapper.c.

Incidentally, on most architectures (bar Mips and Parisc), no
uninitialised variable warning is generated by gcc, this is because the
while condition test on continue is optimised out and not performed
(when executing continue zlib_err has not been changed since entering
the loop, and logically if the while condition was true previously, then
it's still true).

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
Reported-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-26 10:50:05 +10:00
Phillip Lougher
8fcd97216f Squashfs: move squashfs_i() definition from squashfs.h
Move squashfs_i() definition out of squashfs.h, this eliminates
the need to #include squashfs_fs_i.h from numerous files.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
2011-01-13 21:24:15 +00:00
Phillip Lougher
e0d1f70010 squashfs: fix potential buffer over-run on 4K block file systems
Sizing the buffer based on block size is incorrect, leading
to a potential buffer over-run on 4K block size file systems
(because the metadata block size is always 8K).  This bug
doesn't seem have triggered because 4K block size file systems
are not default, and also because metadata blocks after
compression tend to be less than 4K.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
2010-04-25 02:09:05 +01:00
Phillip Lougher
4c0f0bb235 Squashfs: add a decompressor framework
This adds a decompressor framework which allows multiple compression
algorithms to be cleanly supported.

Also update zlib wrapper and other code to use the new framework.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
2010-01-20 21:47:47 +00:00
Phillip Lougher
f1a40359f8 Squashfs: factor out remaining zlib dependencies into separate wrapper file
Move zlib buffer init/destroy code into separate wrapper file.  Also
make zlib z_stream field a void * removing the need to include zlib.h
for most files.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
2010-01-20 21:47:47 +00:00
Phillip Lougher
e6a6d37955 Squashfs: move zlib decompression wrapper code into a separate file
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
2010-01-20 21:47:46 +00:00
Phillip Lougher
363911d027 Squashfs: Valid filesystems are flagged as bad by the corrupted fs patch
The corrupted filesystem patch added a check against zlib trying to
output too much data in the presence of data corruption.  This check
triggered if zlib_inflate asked to be called again (Z_OK) with
avail_out == 0 and no more output buffers available.  This check proves
to be rather dumb, as it incorrectly catches the case where zlib has
generated all the output, but there are still input bytes to be processed.

This patch does a number of things.  It removes the original check and
replaces it with code to not move to the next output buffer if there
are no more output buffers available, relying on zlib to error if it
wants an extra output buffer in the case of data corruption.  It
also replaces the Z_NO_FLUSH flag with the more correct Z_SYNC_FLUSH
flag, and makes the error messages more understandable to
non-technical users.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
Reported-by: Stefan Lippers-Hollmann <s.L-H@gmx.de>
2009-03-12 03:23:48 +00:00
Phillip Lougher
118e1ef6fa Squashfs: Fix oops when reading fsfuzzer corrupted filesystems
This fixes a code regression caused by the recent mainlining changes.
The recent code changes call zlib_inflate repeatedly, decompressing into
separate 4K buffers, this code didn't check for the possibility that
zlib_inflate might ask for too many buffers when decompressing corrupted
data.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
2009-03-05 00:31:12 +00:00
Phillip Lougher
e2780ab159 Squashfs: block operations
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
2009-01-05 08:46:27 +00:00