virtiofs: add filesystem context source name check

In certain scenarios, for example, during fuzz testing, the source
name may be NULL, which could lead to a kernel panic. Therefore, an
extra check for the source name should be added.

Fixes: a62a8ef9d97d ("virtio-fs: add virtiofs filesystem")
Cc: <stable@vger.kernel.org> # all LTS kernels
Signed-off-by: Xiangsheng Hou <xiangsheng.hou@mediatek.com>
Link: https://lore.kernel.org/20250407115111.25535-1-xiangsheng.hou@mediatek.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 2c7b24cb67adb2cb329ed545f56f04700aca8b81..53c2626e90e723ad88f1aee69d7507b4f197ab13 100644 (file)
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c
@@ -1669,6 +1669,9 @@ static int virtio_fs_get_tree(struct fs_context *fsc)
        unsigned int virtqueue_size;
        int err = -EIO;
 
+       if (!fsc->source)
+               return invalf(fsc, "No source specified");
+
        /* This gets a reference on virtio_fs object. This ptr gets installed
         * in fc->iq->priv. Once fuse_conn is going away, it calls ->put()
         * to drop the reference to this object.