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ext4: fix EXT4_MAX_LOGICAL_BLOCK macro

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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: d3b6f23f71 ("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>
This commit is contained in:
Ritesh Harjani 2020-05-05 17:43:14 +02:00 committed by Theodore Ts'o
parent 0e698dfa28
commit 9f44eda195
1 changed files with 1 additions and 1 deletions
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2
fs/ext4/ext4.h
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@ -722,7 +722,7 @@ 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