| Message ID | 1671084718-24796-1-git-send-email-quic_subashab@quicinc.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 2d7afdcbc9d32423f177ee12b7c93783aea338fb |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v2] skbuff: Account for tail adjustment during pull operations | expand |
On Wed, 2022-12-14 at 23:11 -0700, Subash Abhinov Kasiviswanathan wrote: > Extending the tail can have some unexpected side effects if a program uses > a helper like BPF_FUNC_skb_pull_data to read partial content beyond the > head skb headlen when all the skbs in the gso frag_list are linear with no > head_frag - > > kernel BUG at net/core/skbuff.c:4219! > pc : skb_segment+0xcf4/0xd2c > lr : skb_segment+0x63c/0xd2c > Call trace: > skb_segment+0xcf4/0xd2c > __udp_gso_segment+0xa4/0x544 > udp4_ufo_fragment+0x184/0x1c0 > inet_gso_segment+0x16c/0x3a4 > skb_mac_gso_segment+0xd4/0x1b0 > __skb_gso_segment+0xcc/0x12c > udp_rcv_segment+0x54/0x16c > udp_queue_rcv_skb+0x78/0x144 > udp_unicast_rcv_skb+0x8c/0xa4 > __udp4_lib_rcv+0x490/0x68c > udp_rcv+0x20/0x30 > ip_protocol_deliver_rcu+0x1b0/0x33c > ip_local_deliver+0xd8/0x1f0 > ip_rcv+0x98/0x1a4 > deliver_ptype_list_skb+0x98/0x1ec > __netif_receive_skb_core+0x978/0xc60 > > Fix this by marking these skbs as GSO_DODGY so segmentation can handle > the tail updates accordingly. > > Fixes: 3dcbdb134f32 ("net: gso: Fix skb_segment splat when splitting gso_size mangled skb having linear-headed frag_list") > Signed-off-by: Sean Tranchetti <quic_stranche@quicinc.com> > Signed-off-by: Subash Abhinov Kasiviswanathan <quic_subashab@quicinc.com> > --- > v2: Fix the issue in __pskb_pull_tail() instead of __bpf_try_make_writable() > as the issue is generic as mentioned by Daniel. Update the commit text > and Fixes tag accordingly. > > net/core/skbuff.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 88fa405..759bede 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -2416,6 +2416,9 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta) > insp = list; > } else { > /* Eaten partially. */ > + if (skb_is_gso(skb) && !list->head_frag && > + skb_headlen(list)) > + skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY; > > if (skb_shared(list)) { > /* Sucks! We need to fork list. :-( */ So essentially the effect here is that we are disabling scatter-gather when we segment this since we will have to allocate new buffers to realign the linear sections. Looks good to me. Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Hello: This patch was applied to netdev/net.git (master) by Jakub Kicinski <kuba@kernel.org>: On Wed, 14 Dec 2022 23:11:58 -0700 you wrote: > Extending the tail can have some unexpected side effects if a program uses > a helper like BPF_FUNC_skb_pull_data to read partial content beyond the > head skb headlen when all the skbs in the gso frag_list are linear with no > head_frag - > > kernel BUG at net/core/skbuff.c:4219! > pc : skb_segment+0xcf4/0xd2c > lr : skb_segment+0x63c/0xd2c > Call trace: > skb_segment+0xcf4/0xd2c > __udp_gso_segment+0xa4/0x544 > udp4_ufo_fragment+0x184/0x1c0 > inet_gso_segment+0x16c/0x3a4 > skb_mac_gso_segment+0xd4/0x1b0 > __skb_gso_segment+0xcc/0x12c > udp_rcv_segment+0x54/0x16c > udp_queue_rcv_skb+0x78/0x144 > udp_unicast_rcv_skb+0x8c/0xa4 > __udp4_lib_rcv+0x490/0x68c > udp_rcv+0x20/0x30 > ip_protocol_deliver_rcu+0x1b0/0x33c > ip_local_deliver+0xd8/0x1f0 > ip_rcv+0x98/0x1a4 > deliver_ptype_list_skb+0x98/0x1ec > __netif_receive_skb_core+0x978/0xc60 > > [...] Here is the summary with links: - [net,v2] skbuff: Account for tail adjustment during pull operations https://git.kernel.org/netdev/net/c/2d7afdcbc9d3 You are awesome, thank you!
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 88fa405..759bede 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2416,6 +2416,9 @@ void *__pskb_pull_tail(struct sk_buff *skb, int delta) insp = list; } else { /* Eaten partially. */ + if (skb_is_gso(skb) && !list->head_frag && + skb_headlen(list)) + skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY; if (skb_shared(list)) { /* Sucks! We need to fork list. :-( */
Extending the tail can have some unexpected side effects if a program uses a helper like BPF_FUNC_skb_pull_data to read partial content beyond the head skb headlen when all the skbs in the gso frag_list are linear with no head_frag - kernel BUG at net/core/skbuff.c:4219! pc : skb_segment+0xcf4/0xd2c lr : skb_segment+0x63c/0xd2c Call trace: skb_segment+0xcf4/0xd2c __udp_gso_segment+0xa4/0x544 udp4_ufo_fragment+0x184/0x1c0 inet_gso_segment+0x16c/0x3a4 skb_mac_gso_segment+0xd4/0x1b0 __skb_gso_segment+0xcc/0x12c udp_rcv_segment+0x54/0x16c udp_queue_rcv_skb+0x78/0x144 udp_unicast_rcv_skb+0x8c/0xa4 __udp4_lib_rcv+0x490/0x68c udp_rcv+0x20/0x30 ip_protocol_deliver_rcu+0x1b0/0x33c ip_local_deliver+0xd8/0x1f0 ip_rcv+0x98/0x1a4 deliver_ptype_list_skb+0x98/0x1ec __netif_receive_skb_core+0x978/0xc60 Fix this by marking these skbs as GSO_DODGY so segmentation can handle the tail updates accordingly. Fixes: 3dcbdb134f32 ("net: gso: Fix skb_segment splat when splitting gso_size mangled skb having linear-headed frag_list") Signed-off-by: Sean Tranchetti <quic_stranche@quicinc.com> Signed-off-by: Subash Abhinov Kasiviswanathan <quic_subashab@quicinc.com> --- v2: Fix the issue in __pskb_pull_tail() instead of __bpf_try_make_writable() as the issue is generic as mentioned by Daniel. Update the commit text and Fixes tag accordingly. net/core/skbuff.c | 3 +++ 1 file changed, 3 insertions(+)