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CVE-2026-99088unknown

net: openvswitch: validate transport header presence in set_ipv6_addr

Impact

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

Source excerpt · Linux

Affected packages

This source has no supported package-version data for matching. You can read the advisory here, but this record alone cannot power a dependency check.

Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

Linux · Linux

Other versions: unaffected

Version / rangeSource status
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before b7b80d204abdc258006f9e17c92b363ab13bb599affected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 6774af7cd17be8f0d0f70de3a749d381b4f2e9daaffected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 2594795fd832f0253826d64ff8976b8ff5fbfe9faffected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 6b8897ba0733f88f0360ea48a970f373f9142de0affected
3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b to before 3c6a4b11330fe424557538a98fca9f0a4c5bf313affected
Linux version evidence

Linux · Linux

Other versions: affected

Version / rangeSource status
3.8affected
0 to before 3.8unaffected
6.6.160 through 6.6.* (inclusive)unaffected
6.12.113 through 6.12.* (inclusive)unaffected
6.18.57 through 6.18.* (inclusive)unaffected
7.2.11 through 7.2.* (inclusive)unaffected
7.3 through * (inclusive)unaffected
Linux version evidence

Original source description

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

net: openvswitch: validate transport header presence in set_ipv6_addr

When executing IPv6 address rewrite actions on IPv6 fragments, set_ipv6_addr() calls update_ipv6_checksum(). If parse_ipv6hdr() processes a non-first IPv6 fragment, it sets key->ip.proto to NEXTHDR_FRAGMENT and returns early without calling skb_set_transport_header().

update_ipv6_checksum() unconditionally evaluates skb_transport_offset() on entry before checking l4_proto. Because skb->transport_header is uninitialized, this triggers a warning under CONFIG_DEBUG_NET=y although it is completely harmless.

Fix this by returning early in update_ipv6_checksum() if l4_proto is NEXTHDR_FRAGMENT. This avoids reading the uninitialized transport offset for fragments while preserving the debug warning for any other protocol where the transport header is unexpectedly missing.

See the syzbot trace:

!skb_transport_header_was_set(skb) WARNING: ./include/linux/skbuff.h:3075 at skb_transport_header include/linux/skbuff.h:3075 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at skb_transport_offset include/linux/skbuff.h:3250 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at update_ipv6_checksum net/openvswitch/actions.c:361 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399, CPU#1: syz-executor463/5635 [...] RIP: 0010:skb_transport_header include/linux/skbuff.h:3075 [inline] RIP: 0010:skb_transport_offset include/linux/skbuff.h:3250 [inline] RIP: 0010:update_ipv6_checksum net/openvswitch/actions.c:361 [inline] RIP: 0010:set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399 [...] Call Trace: <TASK> set_ipv6 net/openvswitch/actions.c:531 [inline] do_execute_actions+0x557e/0x8600 net/openvswitch/actions.c:1366 ovs_execute_actions+0xde/0x520 net/openvswitch/actions.c:1592 ovs_packet_cmd_execute+0xb4f/0xf10 net/openvswitch/datapath.c:705 genl_family_rcv_msg_doit+0x233/0x340 net/netlink/genetlink.c:1114 genl_rcv_msg+0x614/0x7a0 net/netlink/genetlink.c:1209 netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2572 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218 netlink_unicast+0x7bd/0x940 net/netlink/af_netlink.c:1361 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1916 sock_sendmsg_nosec+0x14e/0x190 net/socket.c:800

References