mirror-linux/net
Jiayuan Chen 29c95185ba nexthop: fix IPv6 route referencing IPv4 nexthop
syzbot reported a panic [1] [2].

When an IPv6 nexthop is replaced with an IPv4 nexthop, the has_v4 flag
of all groups containing this nexthop is not updated. This is because
nh_group_v4_update is only called when replacing AF_INET to AF_INET6,
but the reverse direction (AF_INET6 to AF_INET) is missed.

This allows a stale has_v4=false to bypass fib6_check_nexthop, causing
IPv6 routes to be attached to groups that effectively contain only AF_INET
members. Subsequent route lookups then call nexthop_fib6_nh() which
returns NULL for the AF_INET member, leading to a NULL pointer
dereference.

Fix by calling nh_group_v4_update whenever the family changes, not just
AF_INET to AF_INET6.

Reproducer:
	# AF_INET6 blackhole
	ip -6 nexthop add id 1 blackhole
	# group with has_v4=false
	ip nexthop add id 100 group 1
	# replace with AF_INET (no -6), has_v4 stays false
	ip nexthop replace id 1 blackhole
	# pass stale has_v4 check
	ip -6 route add 2001:db8::/64 nhid 100
	# panic
	ping -6 2001:db8::1

[1] https://syzkaller.appspot.com/bug?id=e17283eb2f8dcf3dd9b47fe6f67a95f71faadad0
[2] https://syzkaller.appspot.com/bug?id=8699b6ae54c9f35837d925686208402949e12ef3
Fixes: 7bf4796dd0 ("nexthops: add support for replace")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20260413114522.147784-1-jiayuan.chen@linux.dev
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-04-16 13:48:30 +02:00
..
6lowpan
9p Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
802 Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
8021q Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
appletalk Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
atm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-03-19 14:16:00 -07:00
ax25 net: change sock.sk_ino and sock_i_ino() to u64 2026-03-06 14:31:26 +01:00
batman-adv Here are two batman-adv bugfixes: 2026-04-08 18:50:27 -07:00
bluetooth Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
bpf bpf: reject short IPv4/IPv6 inputs in bpf_prog_test_run_skb 2026-04-12 15:42:57 -07:00
bridge net: bridge: use a stable FDB dst snapshot in RCU readers 2026-04-16 12:47:41 +02:00
caif net: caif: clear client service pointer on teardown 2026-04-14 13:21:54 +02:00
can Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
ceph libceph: Fix potential out-of-bounds access in ceph_handle_auth_reply() 2026-03-11 10:18:56 +01:00
core Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
dcb Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
devlink Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-04-09 13:20:59 -07:00
dns_resolver net: Add SPDX ids to some source files 2026-03-09 18:32:45 -07:00
dsa net: dsa: tag_rtl8_4: set KEEP flag 2026-04-12 09:03:55 -07:00
ethernet bonding: prevent potential infinite loop in bond_header_parse() 2026-03-16 19:29:45 -07:00
ethtool ethtool: strset: check nla_len overflow 2026-04-12 11:23:50 -07:00
handshake treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
hsr net: hsr: emit notification for PRP slave2 changed hw addr on port deletion 2026-04-07 17:06:16 +02:00
ieee802154 net: remove addr_len argument of recvmsg() handlers 2026-03-02 18:17:17 -08:00
ife
ipv4 nexthop: fix IPv6 route referencing IPv4 nexthop 2026-04-16 13:48:30 +02:00
ipv6 Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
iucv net/iucv: Add missing kernel-doc return value descriptions 2026-03-31 20:14:56 -07:00
kcm kcm: fix zero-frag skb in frag_list on partial sendmsg error 2026-02-23 17:26:55 -08:00
key vfs-7.1-rc1.kino 2026-04-13 12:19:01 -07:00
l2tp Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-04-09 13:20:59 -07:00
l3mdev
lapb treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
llc treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
mac80211 Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
mac802154 bonding: prevent potential infinite loop in bond_header_parse() 2026-03-16 19:29:45 -07:00
mctp net: mctp: defer creation of dst after source-address check 2026-04-06 18:06:47 -07:00
mpls Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-04-02 11:03:13 -07:00
mptcp net: use get_random_u{16,32,64}() where appropriate 2026-04-09 19:27:43 -07:00
ncsi net: ncsi: fix skb leak in error paths 2026-03-06 17:34:48 -08:00
netfilter netfilter: require Ethernet MAC header before using eth_hdr() 2026-04-10 12:16:27 +02:00
netlabel Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
netlink Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
netrom treewide: change inode->i_ino from unsigned long to u64 2026-03-06 14:31:28 +01:00
nfc NFC: digital: Bounds check NFC-A cascade depth in SDD response handler 2026-04-12 11:40:45 -07:00
nsh
openvswitch net: use get_random_u{16,32,64}() where appropriate 2026-04-09 19:27:43 -07:00
packet Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
phonet Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
psample treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21 01:02:28 -08:00
psp net: remove EXPORT_IPV6_MOD() and EXPORT_IPV6_MOD_GPL() macros 2026-03-29 11:21:22 -07:00
qrtr Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-04-14 12:04:00 -07:00
rds Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-04-14 12:04:00 -07:00
rfkill net: rfkill: prevent unlimited numbers of rfkill events from being created 2026-04-07 12:35:04 +02:00
rose Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
rxrpc Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-04-09 13:20:59 -07:00
sched net/sched: sch_cake: fix NAT destination port not being updated in cake_update_flowkeys 2026-04-16 13:13:03 +02:00
sctp Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
shaper net: shaper: protect from late creation of hierarchy 2026-03-19 13:47:15 +01:00
smc net/smc: fix double-free of smc_spd_priv when tee() duplicates splice pipe buffer 2026-03-20 18:59:30 -07:00
strparser net: strparser: fix skb_head leak in strp_abort_strp() 2026-04-14 12:37:00 +02:00
sunrpc kernfs: pass struct ns_common instead of const void * for namespace tags 2026-04-09 14:36:52 +02:00
switchdev bridge: No DEV_PATH_BR_VLAN_UNTAG_HW for dsa foreign 2026-03-19 13:14:00 +01:00
tipc net: use get_random_u{16,32,64}() where appropriate 2026-04-09 19:27:43 -07:00
tls Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-04-09 13:20:59 -07:00
unix Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
vmw_vsock Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-04-14 12:04:00 -07:00
wireless Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
x25 vfs-7.1-rc1.kino 2026-04-13 12:19:01 -07:00
xdp Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
xfrm Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-04-09 13:20:59 -07:00
Kconfig
Kconfig.debug
Makefile
compat.c
devres.c
socket.c Networking changes for 7.1. 2026-04-14 18:36:10 -07:00
sysctl_net.c