Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:[EOL][EOL]nexthop: Forbid FDB status change while nexthop is in a group[EOL][EOL]The kernel forbids the creation of non-FDB nexthop groups with FDB[EOL]nexthops:[EOL][EOL] # ip nexthop add id 1 via 192.0.2.1 fdb[EOL] # ip nexthop add id 2 group 1[EOL] Error: Non FDB nexthop group cannot have fdb nexthops.[EOL][EOL]And vice versa:[EOL][EOL] # ip nexthop add id 3 via 192.0.2.2 dev dummy1[EOL] # ip nexthop add id 4 group 3 fdb[EOL] Error: FDB nexthop group can only have fdb nexthops.[EOL][EOL]However, as long as no routes are pointing to a non-FDB nexthop group,[EOL]the kernel allows changing the type of a nexthop from FDB to non-FDB and[EOL]vice versa:[EOL][EOL] # ip nexthop add id 5 via 192.0.2.2 dev dummy1[EOL] # ip nexthop add id 6 group 5[EOL] # ip nexthop replace id 5 via 192.0.2.2 fdb[EOL] # echo $?[EOL] 0[EOL][EOL]This configuration is invalid and can result in a NPD [1] since FDB[EOL]nexthops are not associated with a nexthop device:[EOL][EOL] # ip route add 198.51.100.1/32 nhid 6[EOL] # ping 198.51.100.1[EOL][EOL]Fix by preventing nexthop FDB status change while the nexthop is in a[EOL]group:[EOL][EOL] # ip nexthop add id 7 via 192.0.2.2 dev dummy1[EOL] # ip nexthop add id 8 group 7[EOL] # ip nexthop replace id 7 via 192.0.2.2 fdb[EOL] Error: Cannot change nexthop FDB status while in a group.[EOL][EOL][1][EOL]BUG: kernel NULL pointer dereference, address: 00000000000003c0[EOL][...][EOL]Oops: Oops: 0000 [#1] SMP[EOL]CPU: 6 UID: 0 PID: 367 Comm: ping Not tainted 6.17.0-rc6-virtme-gb65678cacc03 #1 PREEMPT(voluntary)[EOL]Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014[EOL]RIP: 0010:fib_lookup_good_nhc+0x1e/0x80[EOL][...][EOL]Call Trace:[EOL] <TASK>[EOL] fib_table_lookup+0x541/0x650[EOL] ip_route_output_key_hash_rcu+0x2ea/0x970[EOL] ip_route_output_key_hash+0x55/0x80[EOL] __ip4_datagram_connect+0x250/0x330[EOL] udp_connect+0x2b/0x60[EOL] __sys_connect+0x9c/0xd0[EOL] __x64_sys_connect+0x18/0x20[EOL] do_syscall_64+0xa4/0x2a0[EOL] entry_SYSCALL_64_after_hwframe+0x4b/0x53