CVE-2026-43441

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

net: bonding: Fix nd_tbl NULL dereference when IPv6 is disabled

When booting with the 'ipv6.disable=1' parameter, the ndtbl is never initialized because inet6init() exits before ndiscinit() is called which initializes it. If bonding ARP/NS validation is enabled, an IPv6 NS/NA packet received on a slave can reach bondvalidatena(), which calls bondhasthisip6(). That path calls ipv6chkaddr() and can crash in __ipv6chkaddrandflags().

BUG: kernel NULL pointer dereference, address: 00000000000005d8 Oops: Oops: 0000 [#1] SMP NOPTI RIP: 0010:__ipv6chkaddrandflags+0x69/0x170 Call Trace: <IRQ> ipv6chkaddr+0x1f/0x30 bondvalidatena+0x12e/0x1d0 [bonding] ? __pfxbondhandleframe+0x10/0x10 [bonding] bondrcvvalidate+0x1a0/0x450 [bonding] bondhandleframe+0x5e/0x290 [bonding] ? srsoaliasreturnthunk+0x5/0xfbef5 __netifreceiveskb_core.constprop.0+0x3e8/0xe50 ? srsoaliasreturnthunk+0x5/0xfbef5 ? updatecfsrqloadavg+0x1a/0x240 ? srsoaliasreturnthunk+0x5/0xfbef5 ? __enqueue_entity+0x5e/0x240 __netifreceiveskbonecore+0x39/0xa0 process_backlog+0x9c/0x150 __napipoll+0x30/0x200 ? srsoaliasreturnthunk+0x5/0xfbef5 netrxaction+0x338/0x3b0 handlesoftirqs+0xc9/0x2a0 dosoftirq+0x42/0x60 </IRQ> <TASK> __localbhenable_ip+0x62/0x70 __devqueuexmit+0x2d3/0x1000 ? srsoaliasreturnthunk+0x5/0xfbef5 ? srsoaliasreturnthunk+0x5/0xfbef5 ? packetparseheaders+0x10a/0x1a0 packetsendmsg+0x10da/0x1700 ? kickpool+0x5f/0x140 ? srsoaliasreturn_thunk+0x5/0xfbef5 ? __queue_work+0x12d/0x4f0 __sys_sendto+0x1f3/0x220 _x64syssendto+0x24/0x30 dosyscall64+0x101/0xf80 ? excpagefault+0x6e/0x170 ? srsoaliasreturnthunk+0x5/0xfbef5 entrySYSCALL64afterhwframe+0x77/0x7f </TASK>

Fix this by checking ipv6modenabled() before dispatching IPv6 packets to bondnarcv(). If IPv6 is disabled, return early from bondrcvvalidate() and avoid the path to ipv6chkaddr().