linux/drivers/s390
Jan Höppner cd68c48ea1 s390/dasd: Fix read for ESE with blksize < 4k
When reading unformatted tracks on ESE devices, the corresponding memory
areas are simply set to zero for each segment. This is done incorrectly
for blocksizes < 4096.

There are two problems. First, the increment of dst is done using the
counter of the loop (off), which is increased by blksize every
iteration. This leads to a much bigger increment for dst as actually
intended. Second, the increment of dst is done before the memory area
is set to 0, skipping a significant amount of bytes of memory.

This leads to illegal overwriting of memory and ultimately to a kernel
panic.

This is not a problem with 4k blocksize because
blk_queue_max_segment_size is set to PAGE_SIZE, always resulting in a
single iteration for the inner segment loop (bv.bv_len == blksize). The
incorrectly used 'off' value to increment dst is 0 and the correct
memory area is used.

In order to fix this for blksize < 4k, increment dst correctly using the
blksize and only do it at the end of the loop.

Fixes: 5e2b17e712 ("s390/dasd: Add dynamic formatting support for ESE volumes")
Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Link: https://lore.kernel.org/r/20220505141733.1989450-4-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-05-05 20:08:27 -06:00
..
block s390/dasd: Fix read for ESE with blksize < 4k 2022-05-05 20:08:27 -06:00
char s390: cleanup timer API use 2022-03-27 22:18:39 +02:00
cio s390: cleanup timer API use 2022-03-27 22:18:39 +02:00
crypto s390/zcrypt: fix using the correct variable for sizeof() 2022-03-27 22:18:39 +02:00
net s390/ctcm: fix typo "length to short" -> "length too short" 2022-03-21 13:26:38 +00:00
scsi scsi: zfcp: Fix failed recovery on gone remote port with non-NPIV FCP devices 2022-01-24 23:30:27 -05:00
virtio virtio/s390: get rid of open-coded kvm hypercall 2021-06-28 11:18:28 +02:00
Makefile s390: remove pointless drivers-y in drivers/s390/Makefile 2019-09-16 13:21:51 +02:00