2016-01-29 19:37:52

by Cong Wang

Subject: [PATCH v2 net] nfc: close a race condition 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.

Just lock the sock since this is not a hot path anyway.

Reported-by: Dmitry Vyukov <[email protected]>
Cc: Lauro Ramos Venancio <[email protected]>
Cc: Aloisio Almeida Jr <[email protected]>
Cc: Samuel Ortiz <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
---
net/nfc/llcp_sock.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index ecf0a01..b9edf5f 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -509,6 +509,11 @@ static int llcp_sock_getname(struct socket *sock, struct sockaddr *uaddr,
memset(llcp_addr, 0, sizeof(*llcp_addr));
*len = sizeof(struct sockaddr_nfc_llcp);

+ lock_sock(sk);
+ if (!llcp_sock->dev) {
+ release_sock(sk);
+ return -EBADFD;
+ }
llcp_addr->sa_family = AF_NFC;
llcp_addr->dev_idx = llcp_sock->dev->idx;
llcp_addr->target_idx = llcp_sock->target_idx;
@@ -518,6 +523,7 @@ static int llcp_sock_getname(struct socket *sock, struct sockaddr *uaddr,
llcp_addr->service_name_len = llcp_sock->service_name_len;
memcpy(llcp_addr->service_name, llcp_sock->service_name,
llcp_addr->service_name_len);
+ release_sock(sk);

return 0;
}
--
1.8.3.1

2016-02-25 07:43:45

by Samuel Ortiz

Subject: Re: [PATCH v2 net] nfc: close a race condition in llcp_sock_getname()

Hi Cong,

On Fri, Jan 29, 2016 at 11:37:40AM -0800, 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.
>
> Just lock the sock since this is not a hot path anyway.
>
> Reported-by: Dmitry Vyukov <[email protected]>
> Cc: Lauro Ramos Venancio <[email protected]>
> Cc: Aloisio Almeida Jr <[email protected]>
> Cc: Samuel Ortiz <[email protected]>
> Signed-off-by: Cong Wang <[email protected]>
> ---
> net/nfc/llcp_sock.c | 6 ++++++
> 1 file changed, 6 insertions(+)
Applied as well, thanks.

Cheers,
Samuel.

2016-02-24 18:54:37

by Cong Wang

Subject: Re: [PATCH v2 net] nfc: close a race condition in llcp_sock_getname()

On Fri, Jan 29, 2016 at 11:37 AM, Cong Wang <[email protected]> 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.
>
> Just lock the sock since this is not a hot path anyway.
>
> Reported-by: Dmitry Vyukov <[email protected]>
> Cc: Lauro Ramos Venancio <[email protected]>
> Cc: Aloisio Almeida Jr <[email protected]>
> Cc: Samuel Ortiz <[email protected]>
> Signed-off-by: Cong Wang <[email protected]>


Samuel, please take a look at this one too.


> ---
> net/nfc/llcp_sock.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
> index ecf0a01..b9edf5f 100644
> --- a/net/nfc/llcp_sock.c
> +++ b/net/nfc/llcp_sock.c
> @@ -509,6 +509,11 @@ static int llcp_sock_getname(struct socket *sock, struct sockaddr *uaddr,
> memset(llcp_addr, 0, sizeof(*llcp_addr));
> *len = sizeof(struct sockaddr_nfc_llcp);
>
> + lock_sock(sk);
> + if (!llcp_sock->dev) {
> + release_sock(sk);
> + return -EBADFD;
> + }
> llcp_addr->sa_family = AF_NFC;
> llcp_addr->dev_idx = llcp_sock->dev->idx;
> llcp_addr->target_idx = llcp_sock->target_idx;
> @@ -518,6 +523,7 @@ static int llcp_sock_getname(struct socket *sock, struct sockaddr *uaddr,
> llcp_addr->service_name_len = llcp_sock->service_name_len;
> memcpy(llcp_addr->service_name, llcp_sock->service_name,
> llcp_addr->service_name_len);
> + release_sock(sk);
>
> return 0;
> }
> --
> 1.8.3.1
>