cuse: prevent clone

[ Upstream commit 8217673d07256b22881127bf50dce874d0e51653 ]

For cloned connections cuse_channel_release() will be called more than
once, resulting in use after free.

Prevent device cloning for CUSE, which does not make sense at this point,
and highly unlikely to be used in real life.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/fuse/cuse.c b/fs/fuse/cuse.c
index f057c213c453a8bb2e755d17b5778beb15aab474..e10e2b62ccf453f5e596bc0ec8bbab76af77c92c 100644 (file)
--- a/fs/fuse/cuse.c
+++ b/fs/fuse/cuse.c
@@ -621,6 +621,8 @@ static int __init cuse_init(void)
        cuse_channel_fops.owner         = THIS_MODULE;
        cuse_channel_fops.open          = cuse_channel_open;
        cuse_channel_fops.release       = cuse_channel_release;
+       /* CUSE is not prepared for FUSE_DEV_IOC_CLONE */
+       cuse_channel_fops.unlocked_ioctl        = NULL;
 
        cuse_class = class_create(THIS_MODULE, "cuse");
        if (IS_ERR(cuse_class))