On 7/10/25 12:08, Amir Goldstein wrote:
> We do not support passthrough operations other than read/write on
> regular file, so allowing non-regular backing files makes no sense.
>
> Fixes: efad7153bf93 ("fuse: allow O_PATH fd for FUSE_DEV_IOC_BACKING_OPEN")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> ---
>
> Miklos,
>
> While working on readdir passthrough, I realized that we accidentrly
> allowed creating backing fds for non-regular files.
> This needs to go to stable kernels IMO.
>
> Thanks,
> Amir.
>
> fs/fuse/passthrough.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/fs/fuse/passthrough.c b/fs/fuse/passthrough.c
> index 607ef735ad4a..eb97ac009e75 100644
> --- a/fs/fuse/passthrough.c
> +++ b/fs/fuse/passthrough.c
> @@ -237,6 +237,11 @@ int fuse_backing_open(struct fuse_conn *fc, struct fuse_backing_map *map)
> if (!file)
> goto out;
>
> + /* read/write/splice/mmap passthrough only relevant for regular files */
> + res = d_is_dir(file->f_path.dentry) ? -EISDIR : -EINVAL;
> + if (!d_is_reg(file->f_path.dentry))
> + goto out_fput;
> +
> backing_sb = file_inode(file)->i_sb;
> res = -ELOOP;
> if (backing_sb->s_stack_depth >= fc->max_stack_depth)
LGTM,
Reviewed-by: Bernd Schubert <bschubert@xxxxxxx>
