The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x f6007dce0cd35d634d9be91ef3515a6385dcee16 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2023092039-pulmonary-map-20ae@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: f6007dce0cd3 ("dm: fix a race condition in retrieve_deps") 43e6c111824c ("dm: change from DMWARN to DMERR or DMCRIT for fatal errors") 564b5c5476cd ("dm table: audit all dm_table_get_target() callers") 2aec377a2925 ("dm table: remove dm_table_get_num_targets() wrapper") e810cb78bc4b ("dm: refactor dm_md_mempool allocation") 9571f829f30a ("dm table: fix dm_table_supports_poll to return false if no data devices") 0f14d60a023c ("dm: improve dm_io reference counting") 3b03f7c1242c ("dm: simplify dm_start_io_acct") 4857abf66434 ("dm: simplify dm_io access in dm_split_and_process_bio") 84b98f4ce4d1 ("dm: factor out dm_io_set_error and __dm_io_dec_pending") cfc97abcbe0b ("dm: conditionally enable BIOSET_PERCPU_CACHE for dm_io bioset") 7dd06a2548b2 ("dm: allow dm_accept_partial_bio() for dm_io without duplicate bios") 5291984004ed ("dm: fix bio polling to handle possibile BLK_STS_AGAIN") 4d7bca13dd9a ("dm: consolidate spinlocks in dm_io struct") bd4a6dd241ae ("dm: reduce size of dm_io and dm_target_io structs") 655f3aad7aa4 ("dm: switch dm_target_io booleans over to proper flags") 82f6cdcc3676 ("dm: switch dm_io booleans over to proper flags") e27363472f9b ("dm: factor out dm_io_complete") b7f8dff09827 ("dm: simplify dm_sumbit_bio_remap interface") a92512819b1f ("dm thin: use dm_submit_bio_remap") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From f6007dce0cd35d634d9be91ef3515a6385dcee16 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka <mpatocka@xxxxxxxxxx> Date: Wed, 9 Aug 2023 12:44:20 +0200 Subject: [PATCH] dm: fix a race condition in retrieve_deps There's a race condition in the multipath target when retrieve_deps races with multipath_message calling dm_get_device and dm_put_device. retrieve_deps walks the list of open devices without holding any lock but multipath may add or remove devices to the list while it is running. The end result may be memory corruption or use-after-free memory access. See this description of a UAF with multipath_message(): https://listman.redhat.com/archives/dm-devel/2022-October/052373.html Fix this bug by introducing a new rw semaphore "devices_lock". We grab devices_lock for read in retrieve_deps and we grab it for write in dm_get_device and dm_put_device. Reported-by: Luo Meng <luomeng12@xxxxxxxxxx> Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Tested-by: Li Lingfeng <lilingfeng3@xxxxxxxxxx> Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> diff --git a/drivers/md/dm-core.h b/drivers/md/dm-core.h index 0d93661f88d3..095b9b49aa82 100644 --- a/drivers/md/dm-core.h +++ b/drivers/md/dm-core.h @@ -214,6 +214,7 @@ struct dm_table { /* a list of devices used by this table */ struct list_head devices; + struct rw_semaphore devices_lock; /* events get handed up using this callback */ void (*event_fn)(void *data); diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index f5ed729a8e0c..21ebb6c39394 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1630,6 +1630,8 @@ static void retrieve_deps(struct dm_table *table, struct dm_dev_internal *dd; struct dm_target_deps *deps; + down_read(&table->devices_lock); + deps = get_result_buffer(param, param_size, &len); /* @@ -1644,7 +1646,7 @@ static void retrieve_deps(struct dm_table *table, needed = struct_size(deps, dev, count); if (len < needed) { param->flags |= DM_BUFFER_FULL_FLAG; - return; + goto out; } /* @@ -1656,6 +1658,9 @@ static void retrieve_deps(struct dm_table *table, deps->dev[count++] = huge_encode_dev(dd->dm_dev->bdev->bd_dev); param->data_size = param->data_start + needed; + +out: + up_read(&table->devices_lock); } static int table_deps(struct file *filp, struct dm_ioctl *param, size_t param_size) diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 7d208b2b1a19..37b48f63ae6a 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -135,6 +135,7 @@ int dm_table_create(struct dm_table **result, blk_mode_t mode, return -ENOMEM; INIT_LIST_HEAD(&t->devices); + init_rwsem(&t->devices_lock); if (!num_targets) num_targets = KEYS_PER_NODE; @@ -359,16 +360,20 @@ int __ref dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode, if (dev == disk_devt(t->md->disk)) return -EINVAL; + down_write(&t->devices_lock); + dd = find_device(&t->devices, dev); if (!dd) { dd = kmalloc(sizeof(*dd), GFP_KERNEL); - if (!dd) - return -ENOMEM; + if (!dd) { + r = -ENOMEM; + goto unlock_ret_r; + } r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev); if (r) { kfree(dd); - return r; + goto unlock_ret_r; } refcount_set(&dd->count, 1); @@ -378,12 +383,17 @@ int __ref dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode, } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) { r = upgrade_mode(dd, mode, t->md); if (r) - return r; + goto unlock_ret_r; } refcount_inc(&dd->count); out: + up_write(&t->devices_lock); *result = dd->dm_dev; return 0; + +unlock_ret_r: + up_write(&t->devices_lock); + return r; } EXPORT_SYMBOL(dm_get_device); @@ -419,9 +429,12 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, void dm_put_device(struct dm_target *ti, struct dm_dev *d) { int found = 0; - struct list_head *devices = &ti->table->devices; + struct dm_table *t = ti->table; + struct list_head *devices = &t->devices; struct dm_dev_internal *dd; + down_write(&t->devices_lock); + list_for_each_entry(dd, devices, list) { if (dd->dm_dev == d) { found = 1; @@ -430,14 +443,17 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d) } if (!found) { DMERR("%s: device %s not in table devices list", - dm_device_name(ti->table->md), d->name); - return; + dm_device_name(t->md), d->name); + goto unlock_ret; } if (refcount_dec_and_test(&dd->count)) { - dm_put_table_device(ti->table->md, d); + dm_put_table_device(t->md, d); list_del(&dd->list); kfree(dd); } + +unlock_ret: + up_write(&t->devices_lock); } EXPORT_SYMBOL(dm_put_device);
