From 2b4fc4a191ca24878592e6e9904b83b02873aaaa Mon Sep 17 00:00:00 2001 From: Nicolas Pitre Date: Tue, 30 Oct 2018 13:26:15 -0400 Subject: [PATCH] Cramfs: fix abad comparison when wrap-arounds occur 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 Signed-off-by: Nicolas Pitre Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- fs/cramfs/inode.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c index 355c522..a6c9c2d 100644 --- a/fs/cramfs/inode.c +++ b/fs/cramfs/inode.c @@ -185,7 +185,8 @@ static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned i continue; blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_CACHE_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; } -- 2.7.4