Re: [Patch net] nfc: check sock state in llcp_sock_getname()
On Sat, Jan 2, 2016 at 12:03 AM, Dmitry Vyukov wrote: > On Sat, Jan 2, 2016 at 1:34 AM, Cong Wang wrote: >> llcp_sock_getname() checks llcp_sock->dev to make sure >> llcp_sock is already connected or bound, however, we could >> be in the middle of llcp_sock_bind() where llcp_sock->dev >> is bound and llcp_sock->service_name_len is set, >> but llcp_sock->service_name is not, in this case we would >> lead to copy some bytes from a NULL pointer. >> >> We should just check if sk->sk_state is still closed since >> both connect() and bind() will update this state at the end. > > Hi Cong, > > This is still racy. If you want to play lock-free then you also need > proper memory barriers. Stores to sk_state need to be > smp_store_release, while the load needs to be smp_load_acquire. > Otherwise getname still can see partially initialized socket. > Right... Or just lock sock perhaps. I will update my patch. Thanks! -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [Patch net] nfc: check sock state in llcp_sock_getname()
On Sat, Jan 2, 2016 at 1:34 AM, Cong Wang wrote:
> llcp_sock_getname() checks llcp_sock->dev to make sure
> llcp_sock is already connected or bound, however, we could
> be in the middle of llcp_sock_bind() where llcp_sock->dev
> is bound and llcp_sock->service_name_len is set,
> but llcp_sock->service_name is not, in this case we would
> lead to copy some bytes from a NULL pointer.
>
> We should just check if sk->sk_state is still closed since
> both connect() and bind() will update this state at the end.
Hi Cong,
This is still racy. If you want to play lock-free then you also need
proper memory barriers. Stores to sk_state need to be
smp_store_release, while the load needs to be smp_load_acquire.
Otherwise getname still can see partially initialized socket.
> Reported-by: Dmitry Vyukov
> Cc: Lauro Ramos Venancio
> Cc: Aloisio Almeida Jr
> Cc: Samuel Ortiz
> Signed-off-by: Cong Wang
> ---
> net/nfc/llcp_sock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
> index ecf0a01..5a91997 100644
> --- a/net/nfc/llcp_sock.c
> +++ b/net/nfc/llcp_sock.c
> @@ -500,7 +500,7 @@ static int llcp_sock_getname(struct socket *sock, struct
> sockaddr *uaddr,
> struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
> DECLARE_SOCKADDR(struct sockaddr_nfc_llcp *, llcp_addr, uaddr);
>
> - if (llcp_sock == NULL || llcp_sock->dev == NULL)
> + if (llcp_sock == NULL || sk->sk_state == LLCP_CLOSED)
> return -EBADFD;
>
> pr_debug("%p %d %d %d\n", sk, llcp_sock->target_idx,
> --
> 1.8.3.1
>
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[Patch net] nfc: check sock state in llcp_sock_getname()
llcp_sock_getname() checks llcp_sock->dev to make sure
llcp_sock is already connected or bound, however, we could
be in the middle of llcp_sock_bind() where llcp_sock->dev
is bound and llcp_sock->service_name_len is set,
but llcp_sock->service_name is not, in this case we would
lead to copy some bytes from a NULL pointer.
We should just check if sk->sk_state is still closed since
both connect() and bind() will update this state at the end.
Reported-by: Dmitry Vyukov
Cc: Lauro Ramos Venancio
Cc: Aloisio Almeida Jr
Cc: Samuel Ortiz
Signed-off-by: Cong Wang
---
net/nfc/llcp_sock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index ecf0a01..5a91997 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -500,7 +500,7 @@ static int llcp_sock_getname(struct socket *sock, struct
sockaddr *uaddr,
struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
DECLARE_SOCKADDR(struct sockaddr_nfc_llcp *, llcp_addr, uaddr);
- if (llcp_sock == NULL || llcp_sock->dev == NULL)
+ if (llcp_sock == NULL || sk->sk_state == LLCP_CLOSED)
return -EBADFD;
pr_debug("%p %d %d %d\n", sk, llcp_sock->target_idx,
--
1.8.3.1
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