NULL Pointer Dereference Affecting kernel-rt-64k-modules-partner package, versions *
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Start learning- Snyk IDSNYK-RHEL9-KERNELRT64KMODULESPARTNER-13589784
- published17 Oct 2025
- disclosed15 Oct 2025
Introduced: 15 Oct 2025
CVE-2025-39980 (opens in a new tab)How to fix?
There is no fixed version for RHEL:9 kernel-rt-64k-modules-partner.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-rt-64k-modules-partner package and not the kernel-rt-64k-modules-partner package as distributed by RHEL.
See How to fix? for RHEL:9 relevant fixed versions and status.
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
References
- https://access.redhat.com/security/cve/CVE-2025-39980
- https://git.kernel.org/stable/c/0e7bfe7a268ccbd7859730c529161cafbf44637c
- https://git.kernel.org/stable/c/24046d31f6f92220852d393d510b6062843e3fbd
- https://git.kernel.org/stable/c/390b3a300d7872cef9588f003b204398be69ce08
- https://git.kernel.org/stable/c/8dd4aa0122885f710930de135af2adc4ccc3238f
- https://git.kernel.org/stable/c/e1e87ac0daacd51f522ecd1645cd76b5809303ed
- https://git.kernel.org/stable/c/ec428fff792b7bd15b248dafca2e654b666b1304
- https://git.kernel.org/stable/c/f0e49fd13afe9dea7a09a1c9537fd00cea22badb