4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Nicolas Pitre nicolas.pitre@linaro.org
commit 672ca9dd13f1aca0c17516f76fc5b0e8344b3e46 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/cramfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -186,7 +186,8 @@ static void *cramfs_read(struct super_bl continue; blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT; blk_offset += offset; - if (blk_offset + len > BUFFER_SIZE) + if (blk_offset > BUFFER_SIZE || + blk_offset + len > BUFFER_SIZE) continue; return read_buffers[i] + blk_offset; }