dm: fix dm-raid crash if md_handle_request() splits bio
Commitca522482e3
("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>
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@ -3095,6 +3095,7 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
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INIT_WORK(&rs->md.event_work, do_table_event);
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INIT_WORK(&rs->md.event_work, do_table_event);
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ti->private = rs;
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ti->private = rs;
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ti->num_flush_bios = 1;
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ti->num_flush_bios = 1;
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ti->needs_bio_set_dev = true;
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/* Restore any requested new layout for conversion decision */
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/* Restore any requested new layout for conversion decision */
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rs_config_restore(rs, &rs_layout);
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rs_config_restore(rs, &rs_layout);
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@ -574,9 +574,6 @@ static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
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struct bio *clone;
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struct bio *clone;
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clone = bio_alloc_clone(NULL, bio, GFP_NOIO, &md->mempools->io_bs);
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clone = bio_alloc_clone(NULL, bio, GFP_NOIO, &md->mempools->io_bs);
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/* Set default bdev, but target must bio_set_dev() before issuing IO */
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clone->bi_bdev = md->disk->part0;
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tio = clone_to_tio(clone);
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tio = clone_to_tio(clone);
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tio->flags = 0;
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tio->flags = 0;
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dm_tio_set_flag(tio, DM_TIO_INSIDE_DM_IO);
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dm_tio_set_flag(tio, DM_TIO_INSIDE_DM_IO);
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@ -609,6 +606,7 @@ static void free_io(struct dm_io *io)
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static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti,
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static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti,
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unsigned target_bio_nr, unsigned *len, gfp_t gfp_mask)
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unsigned target_bio_nr, unsigned *len, gfp_t gfp_mask)
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{
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{
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struct mapped_device *md = ci->io->md;
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struct dm_target_io *tio;
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struct dm_target_io *tio;
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struct bio *clone;
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struct bio *clone;
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@ -618,14 +616,10 @@ static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti,
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/* alloc_io() already initialized embedded clone */
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/* alloc_io() already initialized embedded clone */
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clone = &tio->clone;
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clone = &tio->clone;
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} else {
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} else {
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struct mapped_device *md = ci->io->md;
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clone = bio_alloc_clone(NULL, ci->bio, gfp_mask,
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clone = bio_alloc_clone(NULL, ci->bio, gfp_mask,
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&md->mempools->bs);
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&md->mempools->bs);
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if (!clone)
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if (!clone)
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return NULL;
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return NULL;
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/* Set default bdev, but target must bio_set_dev() before issuing IO */
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clone->bi_bdev = md->disk->part0;
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/* REQ_DM_POLL_LIST shouldn't be inherited */
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/* REQ_DM_POLL_LIST shouldn't be inherited */
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clone->bi_opf &= ~REQ_DM_POLL_LIST;
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clone->bi_opf &= ~REQ_DM_POLL_LIST;
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@ -641,6 +635,11 @@ static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti,
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tio->len_ptr = len;
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tio->len_ptr = len;
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tio->old_sector = 0;
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tio->old_sector = 0;
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/* Set default bdev, but target must bio_set_dev() before issuing IO */
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clone->bi_bdev = md->disk->part0;
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if (unlikely(ti->needs_bio_set_dev))
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bio_set_dev(clone, md->disk->part0);
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if (len) {
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if (len) {
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clone->bi_iter.bi_size = to_bytes(*len);
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clone->bi_iter.bi_size = to_bytes(*len);
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if (bio_integrity(clone))
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if (bio_integrity(clone))
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@ -373,6 +373,12 @@ struct dm_target {
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* after returning DM_MAPIO_SUBMITTED from its map function.
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* after returning DM_MAPIO_SUBMITTED from its map function.
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*/
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*/
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bool accounts_remapped_io:1;
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bool accounts_remapped_io:1;
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/*
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* Set if the target will submit the DM bio without first calling
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* bio_set_dev(). NOTE: ideally a target should _not_ need this.
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*/
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bool needs_bio_set_dev:1;
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};
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};
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void *dm_per_bio_data(struct bio *bio, size_t data_size);
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void *dm_per_bio_data(struct bio *bio, size_t data_size);
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@ -286,9 +286,9 @@ enum {
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#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
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#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
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#define DM_VERSION_MAJOR 4
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#define DM_VERSION_MAJOR 4
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#define DM_VERSION_MINOR 46
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#define DM_VERSION_MINOR 47
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#define DM_VERSION_PATCHLEVEL 0
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#define DM_VERSION_PATCHLEVEL 0
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#define DM_VERSION_EXTRA "-ioctl (2022-02-22)"
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#define DM_VERSION_EXTRA "-ioctl (2022-07-28)"
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/* Status bits */
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/* Status bits */
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#define DM_READONLY_FLAG (1 << 0) /* In/Out */
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#define DM_READONLY_FLAG (1 << 0) /* In/Out */
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