Description
In the Linux kernel, the following vulnerability has been resolved: nexthop: Forbid FDB status change while nexthop is in a group The kernel forbids the creation of non-FDB nexthop groups with FDB nexthops: # ip nexthop add id 1 via 192.0.2.1 fdb # ip nexthop add id 2 group 1 Error: Non FDB nexthop group cannot have fdb nexthops. And vice versa: # ip nexthop add id 3 via 192.0.2.2 dev dummy1 # ip nexthop add id 4 group 3 fdb Error: FDB nexthop group can only have fdb nexthops. However, as long as no routes are pointing to a non-FDB nexthop group, the kernel allows changing the type of a nexthop from FDB to non-FDB and vice versa: # ip nexthop add id 5 via 192.0.2.2 dev dummy1 # ip nexthop add id 6 group 5 # ip nexthop replace id 5 via 192.0.2.2 fdb # echo $? 0 This configuration is invalid and can result in a NPD [1] since FDB nexthops are not associated with a nexthop device: # ip route add 198.51.100.1/32 nhid 6 # ping 198.51.100.1 Fix by preventing nexthop FDB status change while the nexthop is in a group: # ip nexthop add id 7 via 192.0.2.2 dev dummy1 # ip nexthop add id 8 group 7 # ip nexthop replace id 7 via 192.0.2.2 fdb Error: Cannot change nexthop FDB status while in a group. [1] BUG: kernel NULL pointer dereference, address: 00000000000003c0 [...] Oops: Oops: 0000 [#1] SMP CPU: 6 UID: 0 PID: 367 Comm: ping Not tainted 6.17.0-rc6-virtme-gb65678cacc03 #1 PREEMPT(voluntary) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-4.fc41 04/01/2014 RIP: 0010:fib_lookup_good_nhc+0x1e/0x80 [...] Call Trace: <TASK> fib_table_lookup+0x541/0x650 ip_route_output_key_hash_rcu+0x2ea/0x970 ip_route_output_key_hash+0x55/0x80 __ip4_datagram_connect+0x250/0x330 udp_connect+0x2b/0x60 __sys_connect+0x9c/0xd0 __x64_sys_connect+0x18/0x20 do_syscall_64+0xa4/0x2a0 entry_SYSCALL_64_after_hwframe+0x4b/0x53
Product status
38428d68719c454d269cb03b776d8a4b0ad66111 before e1e87ac0daacd51f522ecd1645cd76b5809303ed
38428d68719c454d269cb03b776d8a4b0ad66111 before 0e7bfe7a268ccbd7859730c529161cafbf44637c
38428d68719c454d269cb03b776d8a4b0ad66111 before ec428fff792b7bd15b248dafca2e654b666b1304
38428d68719c454d269cb03b776d8a4b0ad66111 before 24046d31f6f92220852d393d510b6062843e3fbd
38428d68719c454d269cb03b776d8a4b0ad66111 before f0e49fd13afe9dea7a09a1c9537fd00cea22badb
38428d68719c454d269cb03b776d8a4b0ad66111 before 8dd4aa0122885f710930de135af2adc4ccc3238f
38428d68719c454d269cb03b776d8a4b0ad66111 before 390b3a300d7872cef9588f003b204398be69ce08
5.8
Any version before 5.8
5.10.245
5.15.194
6.1.155
6.6.109
6.12.50
6.16.10
6.17
References
git.kernel.org/...c/e1e87ac0daacd51f522ecd1645cd76b5809303ed
git.kernel.org/...c/0e7bfe7a268ccbd7859730c529161cafbf44637c
git.kernel.org/...c/ec428fff792b7bd15b248dafca2e654b666b1304
git.kernel.org/...c/24046d31f6f92220852d393d510b6062843e3fbd
git.kernel.org/...c/f0e49fd13afe9dea7a09a1c9537fd00cea22badb
git.kernel.org/...c/8dd4aa0122885f710930de135af2adc4ccc3238f
git.kernel.org/...c/390b3a300d7872cef9588f003b204398be69ce08
