CVE-2026-98934

In the Linux kernel, the following vulnerability has been resolved:

ipv6: sr: use skb get hash net() in seg6 make flowlabel()

Since commit d58e468b1112 ("flow dissector: implements flow dissector BPF hook") skb flow dissect() needs a net pointer, either from skb->dev, skb->sk, or since commit 3cbf4ffba5ee ("net: plumb network namespace into skb flow dissect") a caller provided pointer.

syzbot was able to reach seg6 make flowlabel() with an skb having neither skb->dev nor skb->sk set: a TIPC UDP bearer sends a discovery message through an IPv4 route using seg6 encap, while net.ipv6.seg6 flowlabel is set to 1.

seg6 make flowlabel() already has a net pointer, use skb get hash net().

WARNING: net/core/flow dissector.c:1131 at skb flow dissect+0x910/0x5368 net/core/flow dissector.c:1126, CPU#0: syz.0.17/4930 Call trace: skb flow dissect+0x910/0x5368 net/core/flow dissector.c:1126 (P) skb get hash net+0xe0/0x29c net/core/flow dissector.c:1903 skb get hash include/linux/skbuff.h:1663 [inline] seg6 make flowlabel+0xcc/0x1ec net/ipv6/seg6 iptunnel.c:132 seg6 do srh encap+0x320/0xbf4 net/ipv6/seg6 iptunnel.c:161 seg6 do srh+0x4b4/0xa44 net/ipv6/seg6 iptunnel.c:431 seg6 output core+0x164/0x688 net/ipv6/seg6 iptunnel.c:681 seg6 output+0x44/0x1ac net/ipv6/seg6 iptunnel.c:744 lwtunnel output+0x3d0/0x664 net/core/lwtunnel.c:356 dst output include/net/dst.h:470 [inline] ip local out+0x110/0x148 net/ipv4/ip output.c:131 iptunnel xmit+0x50c/0xd38 net/ipv4/ip tunnel core.c:97 udp tunnel xmit skb+0x220/0x348 net/ipv4/udp tunnel core.c:187 tipc udp xmit+0x75c/0x9c0 net/tipc/udp media.c:202 tipc udp send msg+0x214/0x374 net/tipc/udp media.c:274 tipc bearer xmit skb+0x260/0x3b0 net/tipc/bearer.c:576 tipc enable bearer net/tipc/bearer.c:366 [inline] tipc nl bearer enable+0xc90/0xfb0 net/tipc/bearer.c:1048 tipc nl bearer enable+0x2c/0x48 net/tipc/bearer.c:1057 genl family rcv msg doit+0x1e4/0x2d4 net/netlink/genetlink.c:1114