From: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
ext4 supports max number of logical blocks in a file to be 0xffffffff.
(This is since ext4_extent's ee_block is __le32).
This means that EXT4_MAX_LOGICAL_BLOCK should be 0xfffffffe (starting
from 0 logical offset). This patch fixes this.
The issue was seen when ext4 moved to iomap_fiemap API and when
overlayfs was mounted on top of ext4. Since overlayfs was missing
filemap_check_ranges(), so it could pass a arbitrary huge length which
lead to overflow of map.m_len logic.
This patch fixes that.
Fixes: d3b6f23f7167 ("ext4: move ext4_fiemap to use iomap framework")
Reported-by: syzbot+77fa5bdb65cc39711820@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ritesh Harjani <riteshh@xxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/20200505154324.3226743-2-hch@xxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
(cherry picked from commit 175efa81feb8405676e0136d97b10380179c92e0)
Signed-off-by: George Kennedy <george.kennedy@xxxxxxxxxx>
---
fs/ext4/ext4.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index bf3eaa9..ae2cb15 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -718,7 +718,7 @@ enum {
#define EXT4_MAX_BLOCK_FILE_PHYS 0xFFFFFFFF
/* Max logical block we can support */
-#define EXT4_MAX_LOGICAL_BLOCK 0xFFFFFFFF
+#define EXT4_MAX_LOGICAL_BLOCK 0xFFFFFFFE
/*
* Structure of an inode on the disk
--
1.8.3.1
