Commit 70f19f58 authored by Steven J. Magnani's avatar Steven J. Magnani Committed by Jan Kara
Browse files

udf: Don't corrupt unalloc spacetable when writing it 



For a UDF filesystem configured with an Unallocated Space Table,
a filesystem operation that triggers an update to the table results
in on-disk corruption that prevents remounting:

  udf_read_tagged: tag version 0x0000 != 0x0002 || 0x0003, block 274

For example:
  1. Create a filesystem
      $ mkudffs --media-type=hd --blocksize=512 --lvid=BUGTEST \
              --vid=BUGTEST --fsid=BUGTEST --space=unalloctable \
              /dev/mmcblk0

  2. Mount it
      # mount /dev/mmcblk0 /mnt

  3. Create a file
      $ echo "No corruption, please" > /mnt/new.file

  4. Umount
      # umount /mnt

  5. Attempt remount
      # mount /dev/mmcblk0 /mnt

This appears to be a longstanding bug caused by zero-initialization of
the Unallocated Space Entry block buffer and only partial repopulation
of required fields before writing to disk.

Commit 0adfb339fd64 ("udf: Fix unalloc space handling in udf_update_inode")
addressed one such field, but several others are required.

Signed-off-by: default avatarSteven J. Magnani <steve@digidescorp.com>
Signed-off-by: default avatarJan Kara <jack@suse.com>
parent 45820c29

fs/udf/inode.c

+7 −12
Original line number Diff line number Diff line
@@ -1652,17 +1652,9 @@ static int udf_update_inode(struct inode *inode, int do_sync) 
		       iinfo->i_ext.i_data, inode->i_sb->s_blocksize -

					sizeof(struct unallocSpaceEntry));

		use->descTag.tagIdent = cpu_to_le16(TAG_IDENT_USE);

		use->descTag.tagLocation =

				cpu_to_le32(iinfo->i_location.logicalBlockNum);

		crclen = sizeof(struct unallocSpaceEntry) +

				iinfo->i_lenAlloc - sizeof(struct tag);

		use->descTag.descCRCLength = cpu_to_le16(crclen);

		use->descTag.descCRC = cpu_to_le16(crc_itu_t(0, (char *)use +

							   sizeof(struct tag),

							   crclen));

		use->descTag.tagChecksum = udf_tag_checksum(&use->descTag);

		crclen = sizeof(struct unallocSpaceEntry);



		goto out;

		goto finish;

	}



	if (UDF_QUERY_FLAG(inode->i_sb, UDF_FLAG_UID_FORGET))
@@ -1782,6 +1774,8 @@ static int udf_update_inode(struct inode *inode, int do_sync) 
		efe->descTag.tagIdent = cpu_to_le16(TAG_IDENT_EFE);

		crclen = sizeof(struct extendedFileEntry);

	}



finish:

	if (iinfo->i_strat4096) {

		fe->icbTag.strategyType = cpu_to_le16(4096);

		fe->icbTag.strategyParameter = cpu_to_le16(1);
@@ -1791,7 +1785,9 @@ static int udf_update_inode(struct inode *inode, int do_sync) 
		fe->icbTag.numEntries = cpu_to_le16(1);

	}



	if (S_ISDIR(inode->i_mode))

	if (iinfo->i_use)

		fe->icbTag.fileType = ICBTAG_FILE_TYPE_USE;

	else if (S_ISDIR(inode->i_mode))

		fe->icbTag.fileType = ICBTAG_FILE_TYPE_DIRECTORY;

	else if (S_ISREG(inode->i_mode))

		fe->icbTag.fileType = ICBTAG_FILE_TYPE_REGULAR;
@@ -1828,7 +1824,6 @@ static int udf_update_inode(struct inode *inode, int do_sync) 
						  crclen));

	fe->descTag.tagChecksum = udf_tag_checksum(&fe->descTag);



out:

	set_buffer_uptodate(bh);

	unlock_buffer(bh);

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