| Message ID | Y9gt5EUizK1UImEP@debian (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 876e8ca8366735a604bac86ff7e2732fc9d85d2d |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: fix NULL pointer in skb_segment_list | expand |
On 1/30/23 9:51 PM, Yan Zhai wrote: > Commit 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.") > introduced UDP listifyed GRO. The segmentation relies on frag_list being > untouched when passing through the network stack. This assumption can be > broken sometimes, where frag_list itself gets pulled into linear area, > leaving frag_list being NULL. When this happens it can trigger > following NULL pointer dereference, and panic the kernel. Reverse the > test condition should fix it. > > [19185.577801][ C1] BUG: kernel NULL pointer dereference, address: > ... > [19185.663775][ C1] RIP: 0010:skb_segment_list+0x1cc/0x390 > ... > [19185.834644][ C1] Call Trace: > [19185.841730][ C1] <TASK> > [19185.848563][ C1] __udp_gso_segment+0x33e/0x510 > [19185.857370][ C1] inet_gso_segment+0x15b/0x3e0 > [19185.866059][ C1] skb_mac_gso_segment+0x97/0x110 > [19185.874939][ C1] __skb_gso_segment+0xb2/0x160 > [19185.883646][ C1] udp_queue_rcv_skb+0xc3/0x1d0 > [19185.892319][ C1] udp_unicast_rcv_skb+0x75/0x90 > [19185.900979][ C1] ip_protocol_deliver_rcu+0xd2/0x200 > [19185.910003][ C1] ip_local_deliver_finish+0x44/0x60 > [19185.918757][ C1] __netif_receive_skb_one_core+0x8b/0xa0 > [19185.927834][ C1] process_backlog+0x88/0x130 > [19185.935840][ C1] __napi_poll+0x27/0x150 > [19185.943447][ C1] net_rx_action+0x27e/0x5f0 > [19185.951331][ C1] ? mlx5_cq_tasklet_cb+0x70/0x160 [mlx5_core] > [19185.960848][ C1] __do_softirq+0xbc/0x25d > [19185.968607][ C1] irq_exit_rcu+0x83/0xb0 > [19185.976247][ C1] common_interrupt+0x43/0xa0 > [19185.984235][ C1] asm_common_interrupt+0x22/0x40 > ... > [19186.094106][ C1] </TASK> > > Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.") > Suggested-by: Daniel Borkmann <daniel@iogearbox.net> > Reviewed-by: Willem de Bruijn <willemb@google.com> > Signed-off-by: Yan Zhai <yan@cloudflare.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> > net/core/skbuff.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index 4a0eb5593275..a31ff4d83ecc 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -4100,7 +4100,7 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb, > > skb_shinfo(skb)->frag_list = NULL; > > - do { > + while (list_skb) { > nskb = list_skb; > list_skb = list_skb->next; > > @@ -4146,8 +4146,7 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb, > if (skb_needs_linearize(nskb, features) && > __skb_linearize(nskb)) > goto err_linearize; > - > - } while (list_skb); > + } > > skb->truesize = skb->truesize - delta_truesize; > skb->data_len = skb->data_len - delta_len; >
Hello: This patch was applied to netdev/net.git (master) by Jakub Kicinski <kuba@kernel.org>: On Mon, 30 Jan 2023 12:51:48 -0800 you wrote: > Commit 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.") > introduced UDP listifyed GRO. The segmentation relies on frag_list being > untouched when passing through the network stack. This assumption can be > broken sometimes, where frag_list itself gets pulled into linear area, > leaving frag_list being NULL. When this happens it can trigger > following NULL pointer dereference, and panic the kernel. Reverse the > test condition should fix it. > > [...] Here is the summary with links: - net: fix NULL pointer in skb_segment_list https://git.kernel.org/netdev/net/c/876e8ca83667 You are awesome, thank you!
diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 4a0eb5593275..a31ff4d83ecc 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -4100,7 +4100,7 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb, skb_shinfo(skb)->frag_list = NULL; - do { + while (list_skb) { nskb = list_skb; list_skb = list_skb->next; @@ -4146,8 +4146,7 @@ struct sk_buff *skb_segment_list(struct sk_buff *skb, if (skb_needs_linearize(nskb, features) && __skb_linearize(nskb)) goto err_linearize; - - } while (list_skb); + } skb->truesize = skb->truesize - delta_truesize; skb->data_len = skb->data_len - delta_len;
Commit 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.") introduced UDP listifyed GRO. The segmentation relies on frag_list being untouched when passing through the network stack. This assumption can be broken sometimes, where frag_list itself gets pulled into linear area, leaving frag_list being NULL. When this happens it can trigger following NULL pointer dereference, and panic the kernel. Reverse the test condition should fix it. [19185.577801][ C1] BUG: kernel NULL pointer dereference, address: ... [19185.663775][ C1] RIP: 0010:skb_segment_list+0x1cc/0x390 ... [19185.834644][ C1] Call Trace: [19185.841730][ C1] <TASK> [19185.848563][ C1] __udp_gso_segment+0x33e/0x510 [19185.857370][ C1] inet_gso_segment+0x15b/0x3e0 [19185.866059][ C1] skb_mac_gso_segment+0x97/0x110 [19185.874939][ C1] __skb_gso_segment+0xb2/0x160 [19185.883646][ C1] udp_queue_rcv_skb+0xc3/0x1d0 [19185.892319][ C1] udp_unicast_rcv_skb+0x75/0x90 [19185.900979][ C1] ip_protocol_deliver_rcu+0xd2/0x200 [19185.910003][ C1] ip_local_deliver_finish+0x44/0x60 [19185.918757][ C1] __netif_receive_skb_one_core+0x8b/0xa0 [19185.927834][ C1] process_backlog+0x88/0x130 [19185.935840][ C1] __napi_poll+0x27/0x150 [19185.943447][ C1] net_rx_action+0x27e/0x5f0 [19185.951331][ C1] ? mlx5_cq_tasklet_cb+0x70/0x160 [mlx5_core] [19185.960848][ C1] __do_softirq+0xbc/0x25d [19185.968607][ C1] irq_exit_rcu+0x83/0xb0 [19185.976247][ C1] common_interrupt+0x43/0xa0 [19185.984235][ C1] asm_common_interrupt+0x22/0x40 ... [19186.094106][ C1] </TASK> Fixes: 3a1296a38d0c ("net: Support GRO/GSO fraglist chaining.") Suggested-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Yan Zhai <yan@cloudflare.com> --- net/core/skbuff.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)