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udf: Do not bother merging very long extents 

When merging very long extents we try to push as much length as possible
to the first extent. However this is unnecessarily complicated and not
really worth the trouble. Furthermore there was a bug in the logic
resulting in corrupting extents in the file as syzbot reproducer shows.
So just don't bother with the merging of extents that are too long
together.

CC: stable@vger.kernel.org
Reported-by: syzbot+60f291a24acecb3c2bd5@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2022-12-16 12:37:51 +01:00
parent 70bfb3a8d6
commit 53cafe1d6d
1 changed files with 2 additions and 17 deletions
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19
fs/udf/inode.c
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@ -997,23 +997,8 @@ static void udf_merge_extents(struct inode *inode, struct kernel_long_ad *laarr,
blocksize - 1) >> blocksize_bits)))) {
if (((li->extLength & UDF_EXTENT_LENGTH_MASK) +
(lip1->extLength & UDF_EXTENT_LENGTH_MASK) +
blocksize - 1) & ~UDF_EXTENT_LENGTH_MASK) {
lip1->extLength = (lip1->extLength -
(li->extLength &
UDF_EXTENT_LENGTH_MASK) +
UDF_EXTENT_LENGTH_MASK) &
~(blocksize - 1);
li->extLength = (li->extLength &
UDF_EXTENT_FLAG_MASK) +
(UDF_EXTENT_LENGTH_MASK + 1) -
blocksize;
lip1->extLocation.logicalBlockNum =
li->extLocation.logicalBlockNum +
((li->extLength &
UDF_EXTENT_LENGTH_MASK) >>
blocksize_bits);
} else {
(lip1->extLength & UDF_EXTENT_LENGTH_MASK) +
blocksize - 1) <= UDF_EXTENT_LENGTH_MASK) {
li->extLength = lip1->extLength +
(((li->extLength &
UDF_EXTENT_LENGTH_MASK) +