[ Upstream commit 15fb05fd286ac57a0802d71624daeb5c1c2d5b07 ]
UDF 2.60 standard states in section 2.2.14.2:
A partition with Access Type 3 (rewritable) shall define a Freed
Space Bitmap or a Freed Space Table, see 2.3.3. All other partitions
shall not define a Freed Space Bitmap or a Freed Space Table.
Rewritable partitions are used on media that require some form of
preprocessing before re-writing data (for example legacy MO). Such
partitions shall use Access Type 3.
Overwritable partitions are used on media that do not require
preprocessing before overwriting data (for example: CD-RW, DVD-RW,
DVD+RW, DVD-RAM, BD-RE, HD DVD-Rewritable). Such partitions shall
use Access Type 4.
however older versions of the standard didn't have this wording and
there are tools out there that create UDF filesystems with rewritable
partitions but that don't contain a Freed Space Bitmap or a Freed Space
Table on media that does not require pre-processing before overwriting a
block. So instead of forcing media with rewritable partition read-only,
base this decision on presence of a Freed Space Bitmap or a Freed Space
Table.
Reported-by: Pali Rohár <pali.rohar@gmail.com>
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Fixes: b085fbe2ef7f ("udf: Fix crash during mount")
Link: https://lore.kernel.org/linux-fsdevel/20200112144735.hj2emsoy4uwsouxz@pali
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
97bc3b7d7a