[PATCH net 1/2] Revert "net/ieee802154: reject zero-sized raw_sendmsg()"

[PATCH net 1/2] Revert "net/ieee802154: reject zero-sized raw_sendmsg()"

[Alexander Aring]

This reverts commit 3a4d061c699bd3eedc80dc97a4b2a2e1af83c6f5.

There is a v2 which does return zero if zero length is given.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 net/ieee802154/socket.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/net/ieee802154/socket.c b/net/ieee802154/socket.c
index cbd0e2ac4ffe..7889e1ef7fad 100644
--- a/net/ieee802154/socket.c
+++ b/net/ieee802154/socket.c
@@ -251,9 +251,6 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 		return -EOPNOTSUPP;
 	}
 
-	if (!size)
-		return -EINVAL;
-
 	lock_sock(sk);
 	if (!sk->sk_bound_dev_if)
 		dev = dev_getfirstbyhwtype(sock_net(sk), ARPHRD_IEEE802154);
-- 
2.31.1

[PATCH net 2/2] net/ieee802154: don't warn zero-sized raw_sendmsg()

[Alexander Aring]

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

syzbot is hitting skb_assert_len() warning at __dev_queue_xmit() [1],
for PF_IEEE802154 socket's zero-sized raw_sendmsg() request is hitting
__dev_queue_xmit() with skb->len == 0.

Since PF_IEEE802154 socket's zero-sized raw_sendmsg() request was
able to return 0, don't call __dev_queue_xmit() if packet length is 0.

  ----------
  #include <sys/socket.h>
  #include <netinet/in.h>

  int main(int argc, char *argv[])
  {
    struct sockaddr_in addr = { .sin_family = AF_INET, .sin_addr.s_addr = htonl(INADDR_LOOPBACK) };
    struct iovec iov = { };
    struct msghdr hdr = { .msg_name = &addr, .msg_namelen = sizeof(addr), .msg_iov = &iov, .msg_iovlen = 1 };
    sendmsg(socket(PF_IEEE802154, SOCK_RAW, 0), &hdr, 0);
    return 0;
  }
  ----------

Note that this might be a sign that commit fd1894224407c484 ("bpf: Don't
redirect packets with invalid pkt_len") should be reverted, for
skb->len == 0 was acceptable for at least PF_IEEE802154 socket.

Link: https://syzkaller.appspot.com/bug?extid=5ea725c25d06fb9114c4 [1]
Reported-by: syzbot <syzbot+5ea725c25d06fb9114c4@syzkaller.appspotmail.com>
Fixes: fd1894224407c484 ("bpf: Don't redirect packets with invalid pkt_len")
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
---
 net/ieee802154/socket.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/ieee802154/socket.c b/net/ieee802154/socket.c
index 7889e1ef7fad..6e55fae4c686 100644
--- a/net/ieee802154/socket.c
+++ b/net/ieee802154/socket.c
@@ -272,6 +272,10 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
 		err = -EMSGSIZE;
 		goto out_dev;
 	}
+	if (!size) {
+		err = 0;
+		goto out_dev;
+	}
 
 	hlen = LL_RESERVED_SPACE(dev);
 	tlen = dev->needed_tailroom;
-- 
2.31.1

Re: [PATCH net 2/2] net/ieee802154: don't warn zero-sized raw_sendmsg()

[Stefan Schmidt]

Hello.

On 05.10.22 03:47, Alexander Aring wrote:
> From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> 
> syzbot is hitting skb_assert_len() warning at __dev_queue_xmit() [1],
> for PF_IEEE802154 socket's zero-sized raw_sendmsg() request is hitting
> __dev_queue_xmit() with skb->len == 0.
> 
> Since PF_IEEE802154 socket's zero-sized raw_sendmsg() request was
> able to return 0, don't call __dev_queue_xmit() if packet length is 0.
> 
>    ----------
>    #include <sys/socket.h>
>    #include <netinet/in.h>
> 
>    int main(int argc, char *argv[])
>    {
>      struct sockaddr_in addr = { .sin_family = AF_INET, .sin_addr.s_addr = htonl(INADDR_LOOPBACK) };
>      struct iovec iov = { };
>      struct msghdr hdr = { .msg_name = &addr, .msg_namelen = sizeof(addr), .msg_iov = &iov, .msg_iovlen = 1 };
>      sendmsg(socket(PF_IEEE802154, SOCK_RAW, 0), &hdr, 0);
>      return 0;
>    }
>    ----------
> 
> Note that this might be a sign that commit fd1894224407c484 ("bpf: Don't
> redirect packets with invalid pkt_len") should be reverted, for
> skb->len == 0 was acceptable for at least PF_IEEE802154 socket.
> 
> Link: https://syzkaller.appspot.com/bug?extid=5ea725c25d06fb9114c4 [1]
> Reported-by: syzbot <syzbot+5ea725c25d06fb9114c4@syzkaller.appspotmail.com>
> Fixes: fd1894224407c484 ("bpf: Don't redirect packets with invalid pkt_len")
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Signed-off-by: Alexander Aring <aahringo@redhat.com>
> ---
>   net/ieee802154/socket.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/net/ieee802154/socket.c b/net/ieee802154/socket.c
> index 7889e1ef7fad..6e55fae4c686 100644
> --- a/net/ieee802154/socket.c
> +++ b/net/ieee802154/socket.c
> @@ -272,6 +272,10 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
>   		err = -EMSGSIZE;
>   		goto out_dev;
>   	}
> +	if (!size) {
> +		err = 0;
> +		goto out_dev;
> +	}
>   
>   	hlen = LL_RESERVED_SPACE(dev);
>   	tlen = dev->needed_tailroom;

This patch has been applied to the wpan tree and will be
part of the next pull request to net. Thanks!

regards
Stefan Schmidt

Re: [PATCH net 1/2] Revert "net/ieee802154: reject zero-sized raw_sendmsg()"

[Stefan Schmidt]

Hello.

On 05.10.22 03:47, Alexander Aring wrote:
> This reverts commit 3a4d061c699bd3eedc80dc97a4b2a2e1af83c6f5.
> 
> There is a v2 which does return zero if zero length is given.
> 
> Signed-off-by: Alexander Aring <aahringo@redhat.com>
> ---
>   net/ieee802154/socket.c | 3 ---
>   1 file changed, 3 deletions(-)
> 
> diff --git a/net/ieee802154/socket.c b/net/ieee802154/socket.c
> index cbd0e2ac4ffe..7889e1ef7fad 100644
> --- a/net/ieee802154/socket.c
> +++ b/net/ieee802154/socket.c
> @@ -251,9 +251,6 @@ static int raw_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)
>   		return -EOPNOTSUPP;
>   	}
>   
> -	if (!size)
> -		return -EINVAL;
> -
>   	lock_sock(sk);
>   	if (!sk->sk_bound_dev_if)
>   		dev = dev_getfirstbyhwtype(sock_net(sk), ARPHRD_IEEE802154);

This patch has been applied to the wpan tree and will be
part of the next pull request to net. Thanks!

regards
Stefan Schmidt