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 backs
to the original value by unscanning btrfs devices, it is safe to revert
them here.
Fixes: 79787eaab461 ("btrfs: replace many BUG_ONs with proper error handling")
Signed-off-by: Naohiro Aota <na...@elisp.net>
---
fs/btrfs/volumes.c | 28 +++++++++++++++++++++++-----
1 file changed, 23 insertions(+), 5 deletions(-)
This patch applies on master, but not on kdave/for-next because of
74b9f4e186eb ("btrfs: declare fs_devices in btrfs_init_new_device()")
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1da162928d1a..5f0512fffa52 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2410,7 +2410,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info,
const char *device_path
struct list_head *devices;
struct super_block *sb = fs_info->sb;
struct rcu_string *name;
- u64 tmp;
+ u64 orig_super_total_bytes, orig_super_num_devices;
int seeding_dev = 0;
int ret = 0;
bool unlocked = false;
@@ -2509,12 +2509,14 @@ int btrfs_init_new_device(struct btrfs_fs_info
*fs_info, const char *device_path
if (!blk_queue_nonrot(q))
fs_info->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_info->fs_devices, device);
@@ -2594,6 +2596,22 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info,
const char *device_path
error_sysfs:
btrfs_sysfs_rm_device_link(fs_info->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;
--
2.18.0
--
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