From: Pietro Borrello Date: Sat, 4 Feb 2023 17:39:22 +0000 (+0000) Subject: tap: tap_open(): correctly initialize socket uid X-Git-Tag: v6.3-rc1~162^2~130^2 X-Git-Url: https://repo.jachan.dev/linux.git/commitdiff_plain/66b2c338adce tap: tap_open(): correctly initialize socket uid sock_init_data() assumes that the `struct socket` passed in input is contained in a `struct socket_alloc` allocated with sock_alloc(). However, tap_open() passes a `struct socket` embedded in a `struct tap_queue` allocated with sk_alloc(). This causes a type confusion when issuing a container_of() with SOCK_INODE() in sock_init_data() which results in assigning a wrong sk_uid to the `struct sock` in input. On default configuration, the type confused field overlaps with padding bytes between `int vnet_hdr_sz` and `struct tap_dev __rcu *tap` in `struct tap_queue`, which makes the uid of all tap sockets 0, i.e., the root one. Fix the assignment by using sock_init_data_uid(). Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.") Signed-off-by: Pietro Borrello Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller --- diff --git a/drivers/net/tap.c b/drivers/net/tap.c index a2be1994b389..8941aa199ea3 100644 --- a/drivers/net/tap.c +++ b/drivers/net/tap.c @@ -533,7 +533,7 @@ static int tap_open(struct inode *inode, struct file *file) q->sock.state = SS_CONNECTED; q->sock.file = file; q->sock.ops = &tap_socket_ops; - sock_init_data(&q->sock, &q->sk); + sock_init_data_uid(&q->sock, &q->sk, inode->i_uid); q->sk.sk_write_space = tap_sock_write_space; q->sk.sk_destruct = tap_sock_destruct; q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;