[PATCH 5.4 01/61] ext4: fix EXT4_MAX_LOGICAL_BLOCK macro

Sasha Levin
2021-08-24T17:15:22Z

From: Ritesh Harjani <riteshh@linux.ibm.com>

commit 175efa81feb8405676e0136d97b10380179c92e0 upstream.

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@syzkaller.appspotmail.com
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20200505154324.3226743-2-hch@lst.de
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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 bf3eaa903033..ae2cb15d9540 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
--
2.30.2