From 672ca9dd13f1aca0c17516f76fc5b0e8344b3e46 Mon Sep 17 00:00:00 2001
From: Nicolas Pitre <nicolas.pitre@linaro.org>
Date: Tue, 30 Oct 2018 13:26:15 -0400
Subject: [PATCH] Cramfs: fix abad comparison when wrap-arounds occur
Git-commit: 672ca9dd13f1aca0c17516f76fc5b0e8344b3e46
Patch-mainline: v4.20-rc1
References: bsc#1051510
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
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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 f408994fc632..6e000392e4a4 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -202,7 +202,8 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
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;
}
--
2.16.4