Am 04.09.2014 13:09, schrieb Dan Carpenter:
> 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@xxxxxxxxxx>
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index de505d5..741b92b 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -1702,7 +1702,7 @@ 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)
> @@ -1712,27 +1712,31 @@ 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;
this is hard to read.
perhaps it would help to move ptr into the other other
if (ret || !ptr )
goto free_inherit;
both are modified by the call btrfs_ioctl_snap_create_transid().
@Maintainer:
can this really happen ?
More over i would argue that it would nice to rename
ptr in to transid_ptr or so, this is what the code is all about
and it is not obvious for me.
re,
wh
> -out:
> - kfree(vol_args);
> +
> +free_inherit:
> kfree(inherit);
> +free_args:
> + kfree(vol_args);
> return ret;
> }
>
> @@ -2649,7 +2653,7 @@ 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';
> @@ -2667,6 +2671,7 @@ 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;
> }
> --
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