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udf: Do not bother merging very long extents

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commit 53cafe1d6d8ef9f93318e5bfccc0d24f27d41ced upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jan Kara 2022-12-16 12:37:51 +01:00 committed by Greg Kroah-Hartman
parent 0e7d8e2991
commit adac9ac6d2
1 changed files with 2 additions and 17 deletions
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19
fs/udf/inode.c
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@ -1094,23 +1094,8 @@ 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) +