Btrfs: rework error handling in btrfs_mount()
Commits 6c41761f and 45ea6095 introduced the possibility of NULL pointer
dereference on error paths, also we would leave all devices busy and
leak fs_info with all sub-structures on error when trying to mount an
already mounted fs to a different directory.
Fix this by doing all allocations before trying to open any of the
devices, adjust error path for mount-already-mounted-fs case.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 58e9492..629281c 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -891,7 +891,6 @@
struct super_block *s;
struct dentry *root;
struct btrfs_fs_devices *fs_devices = NULL;
- struct btrfs_root *tree_root = NULL;
struct btrfs_fs_info *fs_info = NULL;
fmode_t mode = FMODE_READ;
char *subvol_name = NULL;
@@ -920,15 +919,6 @@
if (error)
return ERR_PTR(error);
- error = btrfs_open_devices(fs_devices, mode, fs_type);
- if (error)
- return ERR_PTR(error);
-
- if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
- error = -EACCES;
- goto error_close_devices;
- }
-
/*
* Setup a dummy root and fs_info for test/set super. This is because
* we don't actually fill this stuff out until open_ctree, but we need
@@ -936,28 +926,36 @@
* then open_ctree will properly initialize everything later.
*/
fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
- if (!fs_info) {
+ if (!fs_info)
+ return ERR_PTR(-ENOMEM);
+
+ fs_info->tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
+ if (!fs_info->tree_root) {
error = -ENOMEM;
- goto error_close_devices;
+ goto error_fs_info;
}
- tree_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS);
- if (!tree_root) {
- error = -ENOMEM;
- goto error_close_devices;
- }
- fs_info->tree_root = tree_root;
+ fs_info->tree_root->fs_info = fs_info;
fs_info->fs_devices = fs_devices;
- tree_root->fs_info = fs_info;
fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
if (!fs_info->super_copy || !fs_info->super_for_commit) {
error = -ENOMEM;
+ goto error_fs_info;
+ }
+
+ error = btrfs_open_devices(fs_devices, mode, fs_type);
+ if (error)
+ goto error_fs_info;
+
+ if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
+ error = -EACCES;
goto error_close_devices;
}
bdev = fs_devices->latest_bdev;
- s = sget(fs_type, btrfs_test_super, btrfs_set_super, tree_root);
+ s = sget(fs_type, btrfs_test_super, btrfs_set_super,
+ fs_info->tree_root);
if (IS_ERR(s)) {
error = PTR_ERR(s);
goto error_close_devices;
@@ -966,7 +964,8 @@
if (s->s_root) {
if ((flags ^ s->s_flags) & MS_RDONLY) {
deactivate_locked_super(s);
- return ERR_PTR(-EBUSY);
+ error = -EBUSY;
+ goto error_close_devices;
}
btrfs_close_devices(fs_devices);
@@ -997,6 +996,7 @@
error_close_devices:
btrfs_close_devices(fs_devices);
+error_fs_info:
free_fs_info(fs_info);
return ERR_PTR(error);
}