* [PATCH net 1/2] net: fix socket refcounting in skb_complete_wifi_ack()
2017-03-04 5:01 [PATCH net 0/2] net: fix possible sock_hold() misuses Eric Dumazet
@ 2017-03-04 5:01 ` Eric Dumazet
2017-03-04 5:43 ` Soheil Hassas Yeganeh
2017-03-04 5:01 ` [PATCH net 2/2] net: fix socket refcounting in skb_complete_tx_timestamp() Eric Dumazet
2017-03-07 22:06 ` [PATCH net 0/2] net: fix possible sock_hold() misuses David Miller
2 siblings, 1 reply; 6+ messages in thread
From: Eric Dumazet @ 2017-03-04 5:01 UTC (permalink / raw)
To: David S . Miller
Cc: netdev, Willem de Bruijn, Alexander Duyck, Johannes Berg,
Soheil Hassas Yeganeh, Eric Dumazet, Eric Dumazet
TX skbs do not necessarily hold a reference on skb->sk->sk_refcnt
By the time TX completion happens, sk_refcnt might be already 0.
sock_hold()/sock_put() would then corrupt critical state, like
sk_wmem_alloc.
Fixes: bf7fa551e0ce ("mac80211: Resolve sk_refcnt/sk_wmem_alloc issue in wifi ack path")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Willem de Bruijn <willemb@google.com>
---
net/core/skbuff.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f3557958e9bf147631a90b51fef0630920acd97b..e2f37a560ec43ccf60a71f190423bd265eccf594 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3893,7 +3893,7 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
{
struct sock *sk = skb->sk;
struct sock_exterr_skb *serr;
- int err;
+ int err = 1;
skb->wifi_acked_valid = 1;
skb->wifi_acked = acked;
@@ -3903,14 +3903,15 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
serr->ee.ee_errno = ENOMSG;
serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
- /* take a reference to prevent skb_orphan() from freeing the socket */
- sock_hold(sk);
-
- err = sock_queue_err_skb(sk, skb);
+ /* Take a reference to prevent skb_orphan() from freeing the socket,
+ * but only if the socket refcount is not zero.
+ */
+ if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) {
+ err = sock_queue_err_skb(sk, skb);
+ sock_put(sk);
+ }
if (err)
kfree_skb(skb);
-
- sock_put(sk);
}
EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
--
2.12.0.rc1.440.g5b76565f74-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH net 1/2] net: fix socket refcounting in skb_complete_wifi_ack()
2017-03-04 5:01 ` [PATCH net 1/2] net: fix socket refcounting in skb_complete_wifi_ack() Eric Dumazet
@ 2017-03-04 5:43 ` Soheil Hassas Yeganeh
0 siblings, 0 replies; 6+ messages in thread
From: Soheil Hassas Yeganeh @ 2017-03-04 5:43 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, netdev, Willem de Bruijn, Alexander Duyck,
Johannes Berg, Eric Dumazet
On Fri, Mar 3, 2017 at 7:01 PM, Eric Dumazet <edumazet@google.com> wrote:
> TX skbs do not necessarily hold a reference on skb->sk->sk_refcnt
> By the time TX completion happens, sk_refcnt might be already 0.
>
> sock_hold()/sock_put() would then corrupt critical state, like
> sk_wmem_alloc.
>
> Fixes: bf7fa551e0ce ("mac80211: Resolve sk_refcnt/sk_wmem_alloc issue in wifi ack path")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Alexander Duyck <alexander.h.duyck@intel.com>
> Cc: Johannes Berg <johannes@sipsolutions.net>
> Cc: Soheil Hassas Yeganeh <soheil@google.com>
> Cc: Willem de Bruijn <willemb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
> ---
> net/core/skbuff.c | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index f3557958e9bf147631a90b51fef0630920acd97b..e2f37a560ec43ccf60a71f190423bd265eccf594 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -3893,7 +3893,7 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
> {
> struct sock *sk = skb->sk;
> struct sock_exterr_skb *serr;
> - int err;
> + int err = 1;
>
> skb->wifi_acked_valid = 1;
> skb->wifi_acked = acked;
> @@ -3903,14 +3903,15 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
> serr->ee.ee_errno = ENOMSG;
> serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
>
> - /* take a reference to prevent skb_orphan() from freeing the socket */
> - sock_hold(sk);
> -
> - err = sock_queue_err_skb(sk, skb);
> + /* Take a reference to prevent skb_orphan() from freeing the socket,
> + * but only if the socket refcount is not zero.
> + */
> + if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) {
> + err = sock_queue_err_skb(sk, skb);
> + sock_put(sk);
> + }
> if (err)
> kfree_skb(skb);
> -
> - sock_put(sk);
> }
> EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
>
> --
> 2.12.0.rc1.440.g5b76565f74-goog
>
Nice fix!
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH net 2/2] net: fix socket refcounting in skb_complete_tx_timestamp()
2017-03-04 5:01 [PATCH net 0/2] net: fix possible sock_hold() misuses Eric Dumazet
2017-03-04 5:01 ` [PATCH net 1/2] net: fix socket refcounting in skb_complete_wifi_ack() Eric Dumazet
@ 2017-03-04 5:01 ` Eric Dumazet
2017-03-04 5:43 ` Soheil Hassas Yeganeh
2017-03-07 22:06 ` [PATCH net 0/2] net: fix possible sock_hold() misuses David Miller
2 siblings, 1 reply; 6+ messages in thread
From: Eric Dumazet @ 2017-03-04 5:01 UTC (permalink / raw)
To: David S . Miller
Cc: netdev, Willem de Bruijn, Alexander Duyck, Johannes Berg,
Soheil Hassas Yeganeh, Eric Dumazet, Eric Dumazet
TX skbs do not necessarily hold a reference on skb->sk->sk_refcnt
By the time TX completion happens, sk_refcnt might be already 0.
sock_hold()/sock_put() would then corrupt critical state, like
sk_wmem_alloc and lead to leaks or use after free.
Fixes: 62bccb8cdb69 ("net-timestamp: Make the clone operation stand-alone from phy timestamping")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Willem de Bruijn <willemb@google.com>
---
net/core/skbuff.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index e2f37a560ec43ccf60a71f190423bd265eccf594..cd4ba8c6b6091651403cf74de8c60ccf69aa3e7b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3828,13 +3828,14 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
if (!skb_may_tx_timestamp(sk, false))
return;
- /* take a reference to prevent skb_orphan() from freeing the socket */
- sock_hold(sk);
-
- *skb_hwtstamps(skb) = *hwtstamps;
- __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
-
- sock_put(sk);
+ /* Take a reference to prevent skb_orphan() from freeing the socket,
+ * but only if the socket refcount is not zero.
+ */
+ if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) {
+ *skb_hwtstamps(skb) = *hwtstamps;
+ __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
+ sock_put(sk);
+ }
}
EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
--
2.12.0.rc1.440.g5b76565f74-goog
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH net 2/2] net: fix socket refcounting in skb_complete_tx_timestamp()
2017-03-04 5:01 ` [PATCH net 2/2] net: fix socket refcounting in skb_complete_tx_timestamp() Eric Dumazet
@ 2017-03-04 5:43 ` Soheil Hassas Yeganeh
0 siblings, 0 replies; 6+ messages in thread
From: Soheil Hassas Yeganeh @ 2017-03-04 5:43 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, netdev, Willem de Bruijn, Alexander Duyck,
Johannes Berg, Eric Dumazet
On Fri, Mar 3, 2017 at 7:01 PM, Eric Dumazet <edumazet@google.com> wrote:
>
> TX skbs do not necessarily hold a reference on skb->sk->sk_refcnt
> By the time TX completion happens, sk_refcnt might be already 0.
>
> sock_hold()/sock_put() would then corrupt critical state, like
> sk_wmem_alloc and lead to leaks or use after free.
>
> Fixes: 62bccb8cdb69 ("net-timestamp: Make the clone operation stand-alone from phy timestamping")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Alexander Duyck <alexander.h.duyck@intel.com>
> Cc: Johannes Berg <johannes@sipsolutions.net>
> Cc: Soheil Hassas Yeganeh <soheil@google.com>
> Cc: Willem de Bruijn <willemb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
> ---
> net/core/skbuff.c | 15 ++++++++-------
> 1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index e2f37a560ec43ccf60a71f190423bd265eccf594..cd4ba8c6b6091651403cf74de8c60ccf69aa3e7b 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -3828,13 +3828,14 @@ void skb_complete_tx_timestamp(struct sk_buff *skb,
> if (!skb_may_tx_timestamp(sk, false))
> return;
>
> - /* take a reference to prevent skb_orphan() from freeing the socket */
> - sock_hold(sk);
> -
> - *skb_hwtstamps(skb) = *hwtstamps;
> - __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
> -
> - sock_put(sk);
> + /* Take a reference to prevent skb_orphan() from freeing the socket,
> + * but only if the socket refcount is not zero.
> + */
> + if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) {
> + *skb_hwtstamps(skb) = *hwtstamps;
> + __skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);
> + sock_put(sk);
> + }
> }
> EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);
>
> --
> 2.12.0.rc1.440.g5b76565f74-goog
>
Thanks for the fix!
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH net 0/2] net: fix possible sock_hold() misuses
2017-03-04 5:01 [PATCH net 0/2] net: fix possible sock_hold() misuses Eric Dumazet
2017-03-04 5:01 ` [PATCH net 1/2] net: fix socket refcounting in skb_complete_wifi_ack() Eric Dumazet
2017-03-04 5:01 ` [PATCH net 2/2] net: fix socket refcounting in skb_complete_tx_timestamp() Eric Dumazet
@ 2017-03-07 22:06 ` David Miller
2 siblings, 0 replies; 6+ messages in thread
From: David Miller @ 2017-03-07 22:06 UTC (permalink / raw)
To: edumazet; +Cc: netdev, willemb, alexander.h.duyck, johannes, soheil,
eric.dumazet
From: Eric Dumazet <edumazet@google.com>
Date: Fri, 3 Mar 2017 21:01:01 -0800
> skb_complete_wifi_ack() and skb_complete_tx_timestamp() currently
> call sock_hold() on sockets that might have transitioned their sk_refcnt
> to zero already.
Series applied and queued up for -stable, thanks.
^ permalink raw reply [flat|nested] 6+ messages in thread