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dm zone: fix NULL pointer dereference in dm_zone_map_bio

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Commit 0fbb4d93b3 ("dm: add dm_submit_bio_remap interface") changed
the alloc_io() function to delay the initialization of struct dm_io's
orig_bio member, leaving it NULL until after the dm_io and associated
user submitted bio is processed by __split_and_process_bio(). This
change causes a NULL pointer dereference in dm_zone_map_bio() when the
original user bio is inspected to detect the need for zone append
command emulation.

Fix this NULL pointer by updating dm_zone_map_bio() to not access
->orig_bio when the same info can be accessed from the clone of the
->orig_bio _before_ any ->map processing. Save off the bio_op() and
bio_sectors() for the clone and then use the saved orig_bio_details as
needed.

Fixes: 0fbb4d93b3 ("dm: add dm_submit_bio_remap interface")
Reported-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Tested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mike Snitzer 2022-04-13 11:06:19 -04:00
parent ce40426fdc
commit 73d7b06e90
1 changed files with 28 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

49
drivers/md/dm-zone.c
View File

@ -360,16 +360,20 @@ static int dm_update_zone_wp_offset(struct mapped_device *md, unsigned int zno,
return 0;
}
struct orig_bio_details {
unsigned int op;
unsigned int nr_sectors;
};
/*
* First phase of BIO mapping for targets with zone append emulation:
* check all BIO that change a zone writer pointer and change zone
* append operations into regular write operations.
*/
static bool dm_zone_map_bio_begin(struct mapped_device *md,
struct bio *orig_bio, struct bio *clone)
unsigned int zno, struct bio *clone)
{
sector_t zsectors = blk_queue_zone_sectors(md->queue);
unsigned int zno = bio_zone_no(orig_bio);
unsigned int zwp_offset = READ_ONCE(md->zwp_offset[zno]);
/*
@ -384,7 +388,7 @@ static bool dm_zone_map_bio_begin(struct mapped_device *md,
WRITE_ONCE(md->zwp_offset[zno], zwp_offset);
}
switch (bio_op(orig_bio)) {
switch (bio_op(clone)) {
case REQ_OP_ZONE_RESET:
case REQ_OP_ZONE_FINISH:
return true;
@ -401,9 +405,8 @@ static bool dm_zone_map_bio_begin(struct mapped_device *md,
* target zone.
*/
clone->bi_opf = REQ_OP_WRITE | REQ_NOMERGE |
(orig_bio->bi_opf & (~REQ_OP_MASK));
clone->bi_iter.bi_sector =
orig_bio->bi_iter.bi_sector + zwp_offset;
(clone->bi_opf & (~REQ_OP_MASK));
clone->bi_iter.bi_sector += zwp_offset;
break;
default:
DMWARN_LIMIT("Invalid BIO operation");
@ -423,11 +426,10 @@ static bool dm_zone_map_bio_begin(struct mapped_device *md,
* data written to a zone. Note that at this point, the remapped clone BIO
* may already have completed, so we do not touch it.
*/
static blk_status_t dm_zone_map_bio_end(struct mapped_device *md,
struct bio *orig_bio,
static blk_status_t dm_zone_map_bio_end(struct mapped_device *md, unsigned int zno,
struct orig_bio_details *orig_bio_details,
unsigned int nr_sectors)
{
unsigned int zno = bio_zone_no(orig_bio);
unsigned int zwp_offset = READ_ONCE(md->zwp_offset[zno]);
/* The clone BIO may already have been completed and failed */
@ -435,7 +437,7 @@ static blk_status_t dm_zone_map_bio_end(struct mapped_device *md,
return BLK_STS_IOERR;
/* Update the zone wp offset */
switch (bio_op(orig_bio)) {
switch (orig_bio_details->op) {
case REQ_OP_ZONE_RESET:
WRITE_ONCE(md->zwp_offset[zno], 0);
return BLK_STS_OK;
@ -452,7 +454,7 @@ static blk_status_t dm_zone_map_bio_end(struct mapped_device *md,
* Check that the target did not truncate the write operation
* emulating a zone append.
*/
if (nr_sectors != bio_sectors(orig_bio)) {
if (nr_sectors != orig_bio_details->nr_sectors) {
DMWARN_LIMIT("Truncated write for zone append");
return BLK_STS_IOERR;
}
@ -488,7 +490,7 @@ static inline void dm_zone_unlock(struct request_queue *q,
bio_clear_flag(clone, BIO_ZONE_WRITE_LOCKED);
}
static bool dm_need_zone_wp_tracking(struct bio *orig_bio)
static bool dm_need_zone_wp_tracking(struct bio *bio)
{
/*
* Special processing is not needed for operations that do not need the
@ -496,15 +498,15 @@ static bool dm_need_zone_wp_tracking(struct bio *orig_bio)
* zones and all operations that do not modify directly a sequential
* zone write pointer.
*/
if (op_is_flush(orig_bio->bi_opf) && !bio_sectors(orig_bio))
if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
return false;
switch (bio_op(orig_bio)) {
switch (bio_op(bio)) {
case REQ_OP_WRITE_ZEROES:
case REQ_OP_WRITE:
case REQ_OP_ZONE_RESET:
case REQ_OP_ZONE_FINISH:
case REQ_OP_ZONE_APPEND:
return bio_zone_is_seq(orig_bio);
return bio_zone_is_seq(bio);
default:
return false;
}
@ -519,8 +521,8 @@ int dm_zone_map_bio(struct dm_target_io *tio)
struct dm_target *ti = tio->ti;
struct mapped_device *md = io->md;
struct request_queue *q = md->queue;
struct bio *orig_bio = io->orig_bio;
struct bio *clone = &tio->clone;
struct orig_bio_details orig_bio_details;
unsigned int zno;
blk_status_t sts;
int r;
@ -529,18 +531,21 @@ int dm_zone_map_bio(struct dm_target_io *tio)
* IOs that do not change a zone write pointer do not need
* any additional special processing.
*/
if (!dm_need_zone_wp_tracking(orig_bio))
if (!dm_need_zone_wp_tracking(clone))
return ti->type->map(ti, clone);
/* Lock the target zone */
zno = bio_zone_no(orig_bio);
zno = bio_zone_no(clone);
dm_zone_lock(q, zno, clone);
orig_bio_details.nr_sectors = bio_sectors(clone);
orig_bio_details.op = bio_op(clone);
/*
* Check that the bio and the target zone write pointer offset are
* both valid, and if the bio is a zone append, remap it to a write.
*/
if (!dm_zone_map_bio_begin(md, orig_bio, clone)) {
if (!dm_zone_map_bio_begin(md, zno, clone)) {
dm_zone_unlock(q, zno, clone);
return DM_MAPIO_KILL;
}
@ -560,7 +565,8 @@ int dm_zone_map_bio(struct dm_target_io *tio)
* The target submitted the clone BIO. The target zone will
* be unlocked on completion of the clone.
*/
sts = dm_zone_map_bio_end(md, orig_bio, *tio->len_ptr);
sts = dm_zone_map_bio_end(md, zno, &orig_bio_details,
*tio->len_ptr);
break;
case DM_MAPIO_REMAPPED:
/*
@ -568,7 +574,8 @@ int dm_zone_map_bio(struct dm_target_io *tio)
* unlock the target zone here as the clone will not be
* submitted.
*/
sts = dm_zone_map_bio_end(md, orig_bio, *tio->len_ptr);
sts = dm_zone_map_bio_end(md, zno, &orig_bio_details,
*tio->len_ptr);
if (sts != BLK_STS_OK)
dm_zone_unlock(q, zno, clone);
break;