From 67a2c45ee7f4f250458279a2e1244679c5d9735c Mon Sep 17 00:00:00 2001 From: Miao Xie Date: Wed, 3 Sep 2014 21:35:43 +0800 Subject: [PATCH] Btrfs: fix use-after-free problem of the device during device replace The problem is: Task0(device scan task) Task1(device replace task) scan_one_device() mutex_lock(&uuid_mutex) device = find_device() mutex_lock(&device_list_mutex) lock_chunk() rm_and_free_source_device unlock_chunk() mutex_unlock(&device_list_mutex) check device Destroying the target device if device replace fails also has the same problem. We fix this problem by locking uuid_mutex during destroying source device or target device, just like the device remove operation. It is a temporary solution, we can fix this problem and make the code more clear by atomic counter in the future. Signed-off-by: Miao Xie Signed-off-by: Chris Mason --- fs/btrfs/dev-replace.c | 3 +++ fs/btrfs/volumes.c | 4 +++- fs/btrfs/volumes.h | 2 ++ 3 files changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c index aa4c82863c73..e9cbbdb72978 100644 --- a/fs/btrfs/dev-replace.c +++ b/fs/btrfs/dev-replace.c @@ -509,6 +509,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info, ret = btrfs_commit_transaction(trans, root); WARN_ON(ret); + mutex_lock(&uuid_mutex); /* keep away write_all_supers() during the finishing procedure */ mutex_lock(&root->fs_info->fs_devices->device_list_mutex); mutex_lock(&root->fs_info->chunk_mutex); @@ -536,6 +537,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info, btrfs_dev_replace_unlock(dev_replace); mutex_unlock(&root->fs_info->chunk_mutex); mutex_unlock(&root->fs_info->fs_devices->device_list_mutex); + mutex_unlock(&uuid_mutex); if (tgt_device) btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device); mutex_unlock(&dev_replace->lock_finishing_cancel_unmount); @@ -591,6 +593,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info, */ mutex_unlock(&root->fs_info->chunk_mutex); mutex_unlock(&root->fs_info->fs_devices->device_list_mutex); + mutex_unlock(&uuid_mutex); /* write back the superblocks */ trans = btrfs_start_transaction(root, 0); diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index d28e1761fdeb..a15c8ac5d5b3 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -50,7 +50,7 @@ static void __btrfs_reset_dev_stats(struct btrfs_device *dev); static void btrfs_dev_stat_print_on_error(struct btrfs_device *dev); static void btrfs_dev_stat_print_on_load(struct btrfs_device *device); -static DEFINE_MUTEX(uuid_mutex); +DEFINE_MUTEX(uuid_mutex); static LIST_HEAD(fs_uuids); static void lock_chunks(struct btrfs_root *root) @@ -1867,6 +1867,7 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info, { struct btrfs_device *next_device; + mutex_lock(&uuid_mutex); WARN_ON(!tgtdev); mutex_lock(&fs_info->fs_devices->device_list_mutex); if (tgtdev->bdev) { @@ -1886,6 +1887,7 @@ void btrfs_destroy_dev_replace_tgtdev(struct btrfs_fs_info *fs_info, call_rcu(&tgtdev->rcu, free_device); mutex_unlock(&fs_info->fs_devices->device_list_mutex); + mutex_unlock(&uuid_mutex); } static int btrfs_find_device_by_path(struct btrfs_root *root, char *device_path, diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h index 76600a3fedbe..2b37da3dd408 100644 --- a/fs/btrfs/volumes.h +++ b/fs/btrfs/volumes.h @@ -24,6 +24,8 @@ #include #include "async-thread.h" +extern struct mutex uuid_mutex; + #define BTRFS_STRIPE_LEN (64 * 1024) struct buffer_head; -- 2.20.1