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ext4: fix argument checking in EXT4_IOC_MOVE_EXT 

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
This commit is contained in:
Theodore Ts'o 2018-10-02 01:34:44 -04:00
parent f456767d33
commit f18b2b83a7
1 changed files with 6 additions and 2 deletions
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8
fs/ext4/move_extent.c
View File

@ -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 "