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authorJan Höppner <hoeppner@linux.ibm.com>2022-05-05 17:17:31 +0300
committerJens Axboe <axboe@kernel.dk>2022-05-06 05:08:27 +0300
commitcd68c48ea15c85f1577a442dc4c285e112ff1b37 (patch)
tree6781300658e3f49e11207d9a478e7a1c3591a8fe /drivers/s390
parent71f3871657370dbbaf942a1c758f64e49a36c70f (diff)
downloadlinux-cd68c48ea15c85f1577a442dc4c285e112ff1b37.tar.xz
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: 5e2b17e712cf ("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>
Diffstat (limited to 'drivers/s390')
-rw-r--r--drivers/s390/block/dasd_eckd.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index 649eba51e048..e46461b4d8a7 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -3285,12 +3285,11 @@ static int dasd_eckd_ese_read(struct dasd_ccw_req *cqr, struct irb *irb)
cqr->proc_bytes = blk_count * blksize;
return 0;
}
- if (dst && !skip_block) {
- dst += off;
+ if (dst && !skip_block)
memset(dst, 0, blksize);
- } else {
+ else
skip_block--;
- }
+ dst += blksize;
blk_count++;
}
}