[PATCH 5.19 25/38] blk-lib: fix blkdev_issue_secure_erase

Greg Kroah-Hartman
2022-09-21T15:50:56Z

From: Mikulas Patocka <mpatocka@redhat.com>

commit c4fa368466cc1b60bb92f867741488930ddd6034 upstream.

There's a bug in blkdev_issue_secure_erase. The statement
"unsigned int len = min_t(sector_t, nr_sects, max_sectors);"
sets the variable "len" to the length in sectors, but the statement
"bio->bi_iter.bi_size = len" treats it as if it were in bytes.
The statements "sector += len << SECTOR_SHIFT" and "nr_sects -= len <<
SECTOR_SHIFT" are thinko.

This patch fixes it.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org # v5.19
Fixes: 44abff2c0b97 ("block: decouple REQ_OP_SECURE_ERASE from REQ_OP_DISCARD")
Link: https://lore.kernel.org/r/alpine.LRH.2.02.2209141549480.28100@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
block/blk-lib.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -311,6 +311,11 @@ int blkdev_issue_secure_erase(struct blo
struct blk_plug plug;
int ret = 0;

+ /* make sure that "len << SECTOR_SHIFT" doesn't overflow */
+ if (max_sectors > UINT_MAX >> SECTOR_SHIFT)
+ max_sectors = UINT_MAX >> SECTOR_SHIFT;
+ max_sectors &= ~bs_mask;
+
if (max_sectors == 0)
return -EOPNOTSUPP;
if ((sector | nr_sects) & bs_mask)
@@ -324,10 +329,10 @@ int blkdev_issue_secure_erase(struct blo

bio = blk_next_bio(bio, bdev, 0, REQ_OP_SECURE_ERASE, gfp);
bio->bi_iter.bi_sector = sector;
- bio->bi_iter.bi_size = len;
+ bio->bi_iter.bi_size = len << SECTOR_SHIFT;

- sector += len << SECTOR_SHIFT;
- nr_sects -= len << SECTOR_SHIFT;
+ sector += len;
+ nr_sects -= len;
if (!nr_sects) {
ret = submit_bio_wait(bio);
bio_put(bio);