Unverified Commit 0dc7117d authored by Moon Hee Lee's avatar Moon Hee Lee Committed by Konstantin Komarov
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fs/ntfs3: reject index allocation if $BITMAP is empty but blocks exist 



Index allocation requires at least one bit in the $BITMAP attribute to
track usage of index entries. If the bitmap is empty while index blocks
are already present, this reflects on-disk corruption.

syzbot triggered this condition using a malformed NTFS image. During a
rename() operation involving a long filename (which spans multiple
index entries), the empty bitmap allowed the name to be added without
valid tracking. Subsequent deletion of the original entry failed with
-ENOENT, due to unexpected index state.

Reject such cases by verifying that the bitmap is not empty when index
blocks exist.

Reported-by: default avatar <syzbot+b0373017f711c06ada64@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=b0373017f711c06ada64


Fixes: d99208b9 ("fs/ntfs3: cancle set bad inode after removing name fails")
Tested-by: default avatar <syzbot+b0373017f711c06ada64@syzkaller.appspotmail.com>
Signed-off-by: default avatarMoon Hee Lee <moonhee.lee.ca@gmail.com>
Signed-off-by: default avatarKonstantin Komarov <almaz.alexandrovich@paragon-software.com>
parent d6831847

fs/ntfs3/index.c

+10 −0
Original line number Diff line number Diff line
@@ -1508,6 +1508,16 @@ static int indx_add_allocate(struct ntfs_index *indx, struct ntfs_inode *ni, 
			bmp_size = bmp_size_v = le32_to_cpu(bmp->res.data_size);

		}



		/*

		 * Index blocks exist, but $BITMAP has zero valid bits.

		 * This implies an on-disk corruption and must be rejected.

		 */

		if (in->name == I30_NAME &&

		    unlikely(bmp_size_v == 0 && indx->alloc_run.count)) {

			err = -EINVAL;

			goto out1;

		}



		bit = bmp_size << 3;

	}