From: Qu Wenruo Date: Wed, 29 Mar 2017 01:33:21 +0000 (+0800) Subject: btrfs: Wait for in-flight bios before freeing target device for raid56 X-Git-Tag: v4.13~759^2~15 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=ae6529c35bcc1c65c12131cef2aea63d8e2ea950;p=mirror_ubuntu-bionic-kernel.git btrfs: Wait for in-flight bios before freeing target device for raid56 When raid56 dev-replace is cancelled by running scrub, we will free target device without waiting for in-flight bios, causing the following NULL pointer deference or general protection failure. BUG: unable to handle kernel NULL pointer dereference at 00000000000005e0 IP: generic_make_request_checks+0x4d/0x610 CPU: 1 PID: 11676 Comm: kworker/u4:14 Tainted: G O 4.11.0-rc2 #72 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 Workqueue: btrfs-endio-raid56 btrfs_endio_raid56_helper [btrfs] task: ffff88002875b4c0 task.stack: ffffc90001334000 RIP: 0010:generic_make_request_checks+0x4d/0x610 Call Trace: ? generic_make_request+0xc7/0x360 generic_make_request+0x24/0x360 ? generic_make_request+0xc7/0x360 submit_bio+0x64/0x120 ? page_in_rbio+0x4d/0x80 [btrfs] ? rbio_orig_end_io+0x80/0x80 [btrfs] finish_rmw+0x3f4/0x540 [btrfs] validate_rbio_for_rmw+0x36/0x40 [btrfs] raid_rmw_end_io+0x7a/0x90 [btrfs] bio_endio+0x56/0x60 end_workqueue_fn+0x3c/0x40 [btrfs] btrfs_scrubparity_helper+0xef/0x620 [btrfs] btrfs_endio_raid56_helper+0xe/0x10 [btrfs] process_one_work+0x2af/0x720 ? process_one_work+0x22b/0x720 worker_thread+0x4b/0x4f0 kthread+0x10f/0x150 ? process_one_work+0x720/0x720 ? kthread_create_on_node+0x40/0x40 ret_from_fork+0x2e/0x40 RIP: generic_make_request_checks+0x4d/0x610 RSP: ffffc90001337bb8 In btrfs_dev_replace_finishing(), we will call btrfs_rm_dev_replace_blocked() to wait bios before destroying the target device when scrub is finished normally. However when dev-replace is aborted, either due to error or cancelled by scrub, we didn't wait for bios, this can lead to use-after-free if there are bios holding the target device. Furthermore, for raid56 scrub, at least 2 places are calling btrfs_map_sblock() without protection of bio_counter, leading to the problem. This patch fixes the problem: 1) Wait for bio_counter before freeing target device when canceling replace 2) When calling btrfs_map_sblock() for raid56, use bio_counter to protect the call. Cc: Liu Bo Signed-off-by: Qu Wenruo Reviewed-by: Liu Bo Signed-off-by: David Sterba --- diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c index de7b2c897fe0..32b2ffbb5717 100644 --- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -546,8 +546,10 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info, mutex_unlock(&fs_info->chunk_mutex); mutex_unlock(&fs_info->fs_devices->device_list_mutex); mutex_unlock(&uuid_mutex); + btrfs_rm_dev_replace_blocked(fs_info); if (tgt_device) btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device); + btrfs_rm_dev_replace_unblocked(fs_info); mutex_unlock(&dev_replace->lock_finishing_cancel_unmount); return scrub_ret; diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c index 7bf65d9a9bd3..d8ea0eb76325 100644 --- a/fs/btrfs/raid56.c +++ b/fs/btrfs/raid56.c @@ -2198,6 +2198,8 @@ static void read_rebuild_work(struct btrfs_work *work) /* * The following code is used to scrub/replace the parity stripe * + * Caller must have already increased bio_counter for getting @bbio. + * * Note: We need make sure all the pages that add into the scrub/replace * raid bio are correct and not be changed during the scrub/replace. That * is those pages just hold metadata or file data with checksum. @@ -2235,6 +2237,12 @@ raid56_parity_alloc_scrub_rbio(struct btrfs_fs_info *fs_info, struct bio *bio, ASSERT(rbio->stripe_npages == stripe_nsectors); bitmap_copy(rbio->dbitmap, dbitmap, stripe_nsectors); + /* + * We have already increased bio_counter when getting bbio, record it + * so we can free it at rbio_orig_end_io(). + */ + rbio->generic_bio_cnt = 1; + return rbio; } @@ -2677,6 +2685,12 @@ raid56_alloc_missing_rbio(struct btrfs_fs_info *fs_info, struct bio *bio, return NULL; } + /* + * When we get bbio, we have already increased bio_counter, record it + * so we can free it at rbio_orig_end_io() + */ + rbio->generic_bio_cnt = 1; + return rbio; } diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 26dbe563fed0..e9612016325f 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -2191,6 +2191,7 @@ static void scrub_missing_raid56_pages(struct scrub_block *sblock) int ret; int i; + btrfs_bio_counter_inc_blocked(fs_info); ret = btrfs_map_sblock(fs_info, BTRFS_MAP_GET_READ_MIRRORS, logical, &length, &bbio); if (ret || !bbio || !bbio->raid_map) @@ -2235,6 +2236,7 @@ static void scrub_missing_raid56_pages(struct scrub_block *sblock) rbio_out: bio_put(bio); bbio_out: + btrfs_bio_counter_dec(fs_info); btrfs_put_bbio(bbio); spin_lock(&sctx->stat_lock); sctx->stat.malloc_errors++; @@ -2778,6 +2780,8 @@ static void scrub_parity_check_and_repair(struct scrub_parity *sparity) goto out; length = sparity->logic_end - sparity->logic_start; + + btrfs_bio_counter_inc_blocked(fs_info); ret = btrfs_map_sblock(fs_info, BTRFS_MAP_WRITE, sparity->logic_start, &length, &bbio); if (ret || !bbio || !bbio->raid_map) @@ -2805,6 +2809,7 @@ static void scrub_parity_check_and_repair(struct scrub_parity *sparity) rbio_out: bio_put(bio); bbio_out: + btrfs_bio_counter_dec(fs_info); btrfs_put_bbio(bbio); bitmap_or(sparity->ebitmap, sparity->ebitmap, sparity->dbitmap, sparity->nsectors);