| From foo@baz Wed 22 May 2019 08:37:51 AM CEST |
| From: Willem de Bruijn <willemb@google.com> |
| Date: Wed, 15 May 2019 13:29:16 -0400 |
| Subject: net: test nouarg before dereferencing zerocopy pointers |
| |
| From: Willem de Bruijn <willemb@google.com> |
| |
| [ Upstream commit 185ce5c38ea76f29b6bd9c7c8c7a5e5408834920 ] |
| |
| Zerocopy skbs without completion notification were added for packet |
| sockets with PACKET_TX_RING user buffers. Those signal completion |
| through the TP_STATUS_USER bit in the ring. Zerocopy annotation was |
| added only to avoid premature notification after clone or orphan, by |
| triggering a copy on these paths for these packets. |
| |
| The mechanism had to define a special "no-uarg" mode because packet |
| sockets already use skb_uarg(skb) == skb_shinfo(skb)->destructor_arg |
| for a different pointer. |
| |
| Before deferencing skb_uarg(skb), verify that it is a real pointer. |
| |
| Fixes: 5cd8d46ea1562 ("packet: copy user buffers before orphan or clone") |
| Signed-off-by: Willem de Bruijn <willemb@google.com> |
| Signed-off-by: David S. Miller <davem@davemloft.net> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| include/linux/skbuff.h | 9 ++++++--- |
| 1 file changed, 6 insertions(+), 3 deletions(-) |
| |
| --- a/include/linux/skbuff.h |
| +++ b/include/linux/skbuff.h |
| @@ -1333,10 +1333,12 @@ static inline void skb_zcopy_clear(struc |
| struct ubuf_info *uarg = skb_zcopy(skb); |
| |
| if (uarg) { |
| - if (uarg->callback == sock_zerocopy_callback) { |
| + if (skb_zcopy_is_nouarg(skb)) { |
| + /* no notification callback */ |
| + } else if (uarg->callback == sock_zerocopy_callback) { |
| uarg->zerocopy = uarg->zerocopy && zerocopy; |
| sock_zerocopy_put(uarg); |
| - } else if (!skb_zcopy_is_nouarg(skb)) { |
| + } else { |
| uarg->callback(uarg, zerocopy); |
| } |
| |
| @@ -2587,7 +2589,8 @@ static inline int skb_orphan_frags(struc |
| { |
| if (likely(!skb_zcopy(skb))) |
| return 0; |
| - if (skb_uarg(skb)->callback == sock_zerocopy_callback) |
| + if (!skb_zcopy_is_nouarg(skb) && |
| + skb_uarg(skb)->callback == sock_zerocopy_callback) |
| return 0; |
| return skb_copy_ubufs(skb, gfp_mask); |
| } |