From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> commit 7c2bd9a39845bfb6d72ddb55ce737650271f6f96 upstream. syzbot is reporting uninitialized value at rpc_sockaddr2uaddr() [1]. This is because syzbot is setting AF_INET6 to "struct sockaddr_in"->sin_family (which is embedded into user-visible "struct nfs_mount_data" structure) despite nfs23_validate_mount_data() cannot pass sizeof(struct sockaddr_in6) bytes of AF_INET6 address to rpc_sockaddr2uaddr(). Since "struct nfs_mount_data" structure is user-visible, we can't change "struct nfs_mount_data" to use "struct sockaddr_storage". Therefore, assuming that everybody is using AF_INET family when passing address via "struct nfs_mount_data"->addr, reject if its sin_family is not AF_INET. [1] https://syzkaller.appspot.com/bug?id=599993614e7cbbf66bc2656a919ab2a95fb5d75c Reported-by: syzbot <syzbot+047a11c361b872896a4f@xxxxxxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/nfs/super.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/nfs/super.c +++ b/fs/nfs/super.c @@ -2044,7 +2044,8 @@ static int nfs23_validate_mount_data(voi memcpy(sap, &data->addr, sizeof(data->addr)); args->nfs_server.addrlen = sizeof(data->addr); args->nfs_server.port = ntohs(data->addr.sin_port); - if (!nfs_verify_server_address(sap)) + if (sap->sa_family != AF_INET || + !nfs_verify_server_address(sap)) goto out_no_address; if (!(data->flags & NFS_MOUNT_TCP))
