UbiquitousOS
/
OpenCloudOS-Kernel
mirror of https://gitee.com/OpenCloudOS/OpenCloudOS-Kernel.git
11
0
Fork 0
Code Issues Projects Releases Wiki Activity

dm: fix dm-raid crash if md_handle_request() splits bio 

Commit ca522482e3 ("dm: pass NULL bdev to bio_alloc_clone")
introduced the optimization to _not_ perform bio_associate_blkg()'s
relatively costly work when DM core clones its bio. But in doing so it
exposed the possibility for DM's cloned bio to alter DM target
behavior (e.g. crash) if a target were to issue IO without first
calling bio_set_dev().

The DM raid target can trigger an MD crash due to its need to split
the DM bio that is passed to md_handle_request(). The split will
recurse to submit_bio_noacct() using a bio with an uninitialized
->bi_blkg. This NULL bio->bi_blkg causes blk_throtl_bio() to
dereference a NULL blkg_to_tg(bio->bi_blkg).

Fix this in DM core by adding a new 'needs_bio_set_dev' target flag that
will make alloc_tio() call bio_set_dev() on behalf of the target.
dm-raid is the only target that requires this flag. bio_set_dev()
initializes the DM cloned bio's ->bi_blkg, using bio_associate_blkg,
before passing the bio to md_handle_request().

Long-term fix would be to audit and refactor MD code to rely on DM to
split its bio, using dm_accept_partial_bio(), but there are MD raid
personalities (e.g. raid1 and raid10) whose implementation are tightly
coupled to handling the bio splitting inline.

Fixes: ca522482e3 ("dm: pass NULL bdev to bio_alloc_clone")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mike Snitzer 2022-07-20 13:58:04 -04:00
parent 7dad24db59
commit 9dd1cd3220
4 changed files with 15 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/md/dm-raid.c
View File

@ -3095,6 +3095,7 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
INIT_WORK(&rs->md.event_work, do_table_event);
ti->private = rs;
ti->num_flush_bios = 1;
ti->needs_bio_set_dev = true;
/* Restore any requested new layout for conversion decision */
rs_config_restore(rs, &rs_layout);

13
drivers/md/dm.c
View File

@ -574,9 +574,6 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
struct bio *clone;
clone = bio_alloc_clone(NULL, bio, GFP_NOIO, &md->mempools->io_bs);
/* Set default bdev, but target must bio_set_dev() before issuing IO */
clone->bi_bdev = md->disk->part0;
tio = clone_to_tio(clone);
tio->flags = 0;
dm_tio_set_flag(tio, DM_TIO_INSIDE_DM_IO);
@ -609,6 +606,7 @@ static void free_io(struct dm_io *io)
static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti,
unsigned target_bio_nr, unsigned *len, gfp_t gfp_mask)
{
struct mapped_device *md = ci->io->md;
struct dm_target_io *tio;
struct bio *clone;
@ -618,14 +616,10 @@ static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti,
/* alloc_io() already initialized embedded clone */
clone = &tio->clone;
} else {
struct mapped_device *md = ci->io->md;
clone = bio_alloc_clone(NULL, ci->bio, gfp_mask,
&md->mempools->bs);
if (!clone)
return NULL;
/* Set default bdev, but target must bio_set_dev() before issuing IO */
clone->bi_bdev = md->disk->part0;
/* REQ_DM_POLL_LIST shouldn't be inherited */
clone->bi_opf &= ~REQ_DM_POLL_LIST;
@ -641,6 +635,11 @@ static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti,
tio->len_ptr = len;
tio->old_sector = 0;
/* Set default bdev, but target must bio_set_dev() before issuing IO */
clone->bi_bdev = md->disk->part0;
if (unlikely(ti->needs_bio_set_dev))
bio_set_dev(clone, md->disk->part0);
if (len) {
clone->bi_iter.bi_size = to_bytes(*len);
if (bio_integrity(clone))

6
include/linux/device-mapper.h
View File

@ -373,6 +373,12 @@ struct dm_target {
* after returning DM_MAPIO_SUBMITTED from its map function.
*/
bool accounts_remapped_io:1;
/*
* Set if the target will submit the DM bio without first calling
* bio_set_dev(). NOTE: ideally a target should _not_ need this.
*/
bool needs_bio_set_dev:1;
};
void *dm_per_bio_data(struct bio *bio, size_t data_size);

4
include/uapi/linux/dm-ioctl.h
View File

@ -286,9 +286,9 @@ enum {
#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
#define DM_VERSION_MAJOR 4
#define DM_VERSION_MINOR 46
#define DM_VERSION_MINOR 47
#define DM_VERSION_PATCHLEVEL 0
#define DM_VERSION_EXTRA "-ioctl (2022-02-22)"
#define DM_VERSION_EXTRA "-ioctl (2022-07-28)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */