Cramfs: fix abad comparison when wrap-arounds occur

It is possible for corrupted filesystem images to produce very large
block offsets that may wrap when a length is added, and wrongly pass
the buffer size test.

Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com>
Signed-off-by: Nicolas Pitre <nico@linaro.org>
Cc: stable@vger.kernel.org
This commit is contained in:
Nicolas Pitre 2018-10-30 13:26:15 -04:00
parent 84df9525b0
commit 672ca9dd13

View File

@ -202,7 +202,8 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
continue; continue;
blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT; blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT;
blk_offset += offset; blk_offset += offset;
if (blk_offset + len > BUFFER_SIZE) if (blk_offset > BUFFER_SIZE ||
blk_offset + len > BUFFER_SIZE)
continue; continue;
return read_buffers[i] + blk_offset; return read_buffers[i] + blk_offset;
} }