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authorDong Chenchen <dongchenchen2@huawei.com>2023-05-11 15:54:40 +0300
committerDavid S. Miller <davem@davemloft.net>2023-05-15 10:40:27 +0300
commitc83b49383b595be50647f0c764a48c78b5f3c4f8 (patch)
tree4c9744972261e038bf7889795655bfc1d38a7907
parentb41caaded077aa8e7617c15e87d0503df8e7739e (diff)
downloadlinux-c83b49383b595be50647f0c764a48c78b5f3c4f8.tar.xz
net: nsh: Use correct mac_offset to unwind gso skb in nsh_gso_segment()
As the call trace shows, skb_panic was caused by wrong skb->mac_header in nsh_gso_segment(): invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 3 PID: 2737 Comm: syz Not tainted 6.3.0-next-20230505 #1 RIP: 0010:skb_panic+0xda/0xe0 call Trace: skb_push+0x91/0xa0 nsh_gso_segment+0x4f3/0x570 skb_mac_gso_segment+0x19e/0x270 __skb_gso_segment+0x1e8/0x3c0 validate_xmit_skb+0x452/0x890 validate_xmit_skb_list+0x99/0xd0 sch_direct_xmit+0x294/0x7c0 __dev_queue_xmit+0x16f0/0x1d70 packet_xmit+0x185/0x210 packet_snd+0xc15/0x1170 packet_sendmsg+0x7b/0xa0 sock_sendmsg+0x14f/0x160 The root cause is: nsh_gso_segment() use skb->network_header - nhoff to reset mac_header in skb_gso_error_unwind() if inner-layer protocol gso fails. However, skb->network_header may be reset by inner-layer protocol gso function e.g. mpls_gso_segment. skb->mac_header reset by the inaccurate network_header will be larger than skb headroom. nsh_gso_segment nhoff = skb->network_header - skb->mac_header; __skb_pull(skb,nsh_len) skb_mac_gso_segment mpls_gso_segment skb_reset_network_header(skb);//skb->network_header+=nsh_len return -EINVAL; skb_gso_error_unwind skb_push(skb, nsh_len); skb->mac_header = skb->network_header - nhoff; // skb->mac_header > skb->headroom, cause skb_push panic Use correct mac_offset to restore mac_header and get rid of nhoff. Fixes: c411ed854584 ("nsh: add GSO support") Reported-by: syzbot+632b5d9964208bfef8c0@syzkaller.appspotmail.com Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/nsh/nsh.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/net/nsh/nsh.c b/net/nsh/nsh.c
index e9ca007718b7..0f23e5e8e03e 100644
--- a/net/nsh/nsh.c
+++ b/net/nsh/nsh.c
@@ -77,13 +77,12 @@ static struct sk_buff *nsh_gso_segment(struct sk_buff *skb,
netdev_features_t features)
{
struct sk_buff *segs = ERR_PTR(-EINVAL);
+ u16 mac_offset = skb->mac_header;
unsigned int nsh_len, mac_len;
__be16 proto;
- int nhoff;
skb_reset_network_header(skb);
- nhoff = skb->network_header - skb->mac_header;
mac_len = skb->mac_len;
if (unlikely(!pskb_may_pull(skb, NSH_BASE_HDR_LEN)))
@@ -108,15 +107,14 @@ static struct sk_buff *nsh_gso_segment(struct sk_buff *skb,
segs = skb_mac_gso_segment(skb, features);
if (IS_ERR_OR_NULL(segs)) {
skb_gso_error_unwind(skb, htons(ETH_P_NSH), nsh_len,
- skb->network_header - nhoff,
- mac_len);
+ mac_offset, mac_len);
goto out;
}
for (skb = segs; skb; skb = skb->next) {
skb->protocol = htons(ETH_P_NSH);
__skb_push(skb, nsh_len);
- skb_set_mac_header(skb, -nhoff);
+ skb->mac_header = mac_offset;
skb->network_header = skb->mac_header + mac_len;
skb->mac_len = mac_len;
}