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btrfs: revert fs_devices state on error of btrfs_init_new_device

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When btrfs hits error after modifying fs_devices in
btrfs_init_new_device() (such as btrfs_add_dev_item() returns error), it
leaves everything as is, but frees allocated btrfs_device. As a result,
fs_devices->devices and fs_devices->alloc_list contain already freed
btrfs_device, leading to later use-after-free bug.

Error path also messes the things like ->num_devices. While they go back
to the original value by unscanning btrfs devices, it is safe to revert
them here.

Fixes: 79787eaab4 ("btrfs: replace many BUG_ONs with proper error handling")
Signed-off-by: Naohiro Aota <naota@elisp.net>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Naohiro Aota 2018-07-27 09:04:55 +09:00 committed by David Sterba
parent 64f64f43c8
commit 39379faaad
1 changed files with 24 additions and 5 deletions
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29
fs/btrfs/volumes.c
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@ -2321,7 +2321,8 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
struct super_block *sb = fs_info->sb;
struct rcu_string *name;
struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
u64 tmp;
u64 orig_super_total_bytes;
u64 orig_super_num_devices;
int seeding_dev = 0;
int ret = 0;
bool unlocked = false;
@ -2417,12 +2418,14 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
if (!blk_queue_nonrot(q))
fs_devices->rotating = 1;
tmp = btrfs_super_total_bytes(fs_info->super_copy);
orig_super_total_bytes = btrfs_super_total_bytes(fs_info->super_copy);
btrfs_set_super_total_bytes(fs_info->super_copy,
round_down(tmp + device->total_bytes, fs_info->sectorsize));
round_down(orig_super_total_bytes + device->total_bytes,
fs_info->sectorsize));
tmp = btrfs_super_num_devices(fs_info->super_copy);
btrfs_set_super_num_devices(fs_info->super_copy, tmp + 1);
orig_super_num_devices = btrfs_super_num_devices(fs_info->super_copy);
btrfs_set_super_num_devices(fs_info->super_copy,
orig_super_num_devices + 1);
/* add sysfs device entry */
btrfs_sysfs_add_device_link(fs_devices, device);
@ -2502,6 +2505,22 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
error_sysfs:
btrfs_sysfs_rm_device_link(fs_devices, device);
mutex_lock(&fs_info->fs_devices->device_list_mutex);
mutex_lock(&fs_info->chunk_mutex);
list_del_rcu(&device->dev_list);
list_del(&device->dev_alloc_list);
fs_info->fs_devices->num_devices--;
fs_info->fs_devices->open_devices--;
fs_info->fs_devices->rw_devices--;
fs_info->fs_devices->total_devices--;
fs_info->fs_devices->total_rw_bytes -= device->total_bytes;
atomic64_sub(device->total_bytes, &fs_info->free_chunk_space);
btrfs_set_super_total_bytes(fs_info->super_copy,
orig_super_total_bytes);
btrfs_set_super_num_devices(fs_info->super_copy,
orig_super_num_devices);
mutex_unlock(&fs_info->chunk_mutex);
mutex_unlock(&fs_info->fs_devices->device_list_mutex);
error_trans:
if (seeding_dev)
sb->s_flags |= SB_RDONLY;