From 862ed307cdb6281d669ac6a3124b109bac9d401c Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 10 Jul 2025 12:08:30 +0200 Subject: fuse: do not allow mapping a non-regular backing file 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@vger.kernel.org Signed-off-by: Amir Goldstein Reviewed-by: Bernd Schubert Signed-off-by: Miklos Szeredi --- fs/fuse/passthrough.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/fs/fuse/passthrough.c +++ b/fs/fuse/passthrough.c @@ -237,6 +237,11 @@ int fuse_backing_open(struct fuse_conn * 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)