From f18b2b83a727a3db208308057d2c7945f368e625 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Tue, 2 Oct 2018 01:34:44 -0400
Subject: [PATCH] ext4: fix argument checking in EXT4_IOC_MOVE_EXT
Git-commit: f18b2b83a727a3db208308057d2c7945f368e625
Patch-mainline: v4.20-rc1
References: bsc#1207092
If the starting block number of either the source or destination file
exceeds the EOF, EXT4_IOC_MOVE_EXT should return EINVAL.
Also fixed the helper function mext_check_coverage() so that if the
logical block is beyond EOF, make it return immediately, instead of
looping until the block number wraps all the away around. This takes
long enough that if there are multiple threads trying to do pound on
an the same inode doing non-sensical things, it can end up triggering
the kernel's soft lockup detector.
Reported-by: syzbot+c61979f6f2cba5cb3c06@syzkaller.appspotmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Acked-by: Jan Kara <jack@suse.cz>
---
fs/ext4/move_extent.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index a409ff70d67b..2f5be02fc6f6 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -516,9 +516,13 @@ mext_check_arguments(struct inode *orig_inode,
orig_inode->i_ino, donor_inode->i_ino);
return -EINVAL;
}
- if (orig_eof < orig_start + *len - 1)
+ if (orig_eof <= orig_start)
+ *len = 0;
+ else if (orig_eof < orig_start + *len - 1)
*len = orig_eof - orig_start;
- if (donor_eof < donor_start + *len - 1)
+ if (donor_eof <= donor_start)
+ *len = 0;
+ else if (donor_eof < donor_start + *len - 1)
*len = donor_eof - donor_start;
if (!*len) {
ext4_debug("ext4 move extent: len should not be 0 "
--
2.35.3