Btrfs: kfree()ing ERR_PTRs

The "inherit" in btrfs_ioctl_snap_create_v2() and "vol_args" in
btrfs_ioctl_rm_dev() are ERR_PTRs so we can't call kfree() on them.

These kind of bugs are "One Err Bugs" where there is just one error
label that does everything.  I could set the "inherit = NULL" and keep
the single out label but it ends up being more complicated that way.  It
makes the code simpler to re-order the unwind so it's in the mirror
order of the allocation and introduce some new error labels.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 15 insertions, 10 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a018ea484d39..8a8e29878c34 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1703,7 +1703,7 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
             ~(BTRFS_SUBVOL_CREATE_ASYNC | BTRFS_SUBVOL_RDONLY |
               BTRFS_SUBVOL_QGROUP_INHERIT)) {
                 ret = -EOPNOTSUPP;
-                goto out;
+                goto free_args;
         }
 
         if (vol_args->flags & BTRFS_SUBVOL_CREATE_ASYNC)
@@ -1713,27 +1713,31 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
         if (vol_args->flags & BTRFS_SUBVOL_QGROUP_INHERIT) {
                 if (vol_args->size > PAGE_CACHE_SIZE) {
                         ret = -EINVAL;
-                        goto out;
+                        goto free_args;
                 }
                 inherit = memdup_user(vol_args->qgroup_inherit, vol_args->size);
                 if (IS_ERR(inherit)) {
                         ret = PTR_ERR(inherit);
-                        goto out;
+                        goto free_args;
                 }
         }
 
         ret = btrfs_ioctl_snap_create_transid(file, vol_args->name,
                                               vol_args->fd, subvol, ptr,
                                               readonly, inherit);
+        if (ret)
+                goto free_inherit;
 
-        if (ret == 0 && ptr &&
-            copy_to_user(arg +
-                         offsetof(struct btrfs_ioctl_vol_args_v2,
-                                  transid), ptr, sizeof(*ptr)))
+        if (ptr && copy_to_user(arg +
+                                offsetof(struct btrfs_ioctl_vol_args_v2,
+                                        transid),
+                                ptr, sizeof(*ptr)))
                 ret = -EFAULT;
-out:
-        kfree(vol_args);
+
+free_inherit:
         kfree(inherit);
+free_args:
+        kfree(vol_args);
         return ret;
 }
 
@@ -2653,7 +2657,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
         vol_args = memdup_user(arg, sizeof(*vol_args));
         if (IS_ERR(vol_args)) {
                 ret = PTR_ERR(vol_args);
-                goto out;
+                goto err_drop;
         }
 
         vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
@@ -2671,6 +2675,7 @@ static long btrfs_ioctl_rm_dev(struct file *file, void __user *arg)
 
 out:
         kfree(vol_args);
+err_drop:
         mnt_drop_write_file(file);
         return ret;
 }