CVE-2026-89789
Published: September 18, 2026Last modified: October 6, 2026
Description
In the Linux kernel, the following vulnerability has been resolved: gtp: add synchronize_net() in gtp_newlink() error path to prevent use-after-free gtp_newlink()'s error path frees tid_hash and addr_hash without waiting for an RCU grace period after clearing sk_user_data. A concurrent gtp_encap_recv() in softirq may still hold the gtp_dev pointer obtained via rcu_dereference_sk_user_data() and access the freed memory. BUG: KASAN: slab-use-after-free in gtp0_pdp_find+0x1f6/0x200 (gtp.c:152) Call Trace: <IRQ> gtp0_pdp_find+0x1f6/0x200 gtp_encap_recv+0x527/0x24b0 udp_queue_rcv_one_skb+0x75f/0xc10 Add synchronize_net() before the kfree calls in out_hashtable, which covers all error paths from both gtp_encap_enable() and gtp_create_sockets().
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 7.8 |
| Attack Vector | LOCAL |
| Attack complexity | LOW |
| Privileges required | LOW |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity impact | HIGH |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | linux-lts | Fixed (6.1.189-r0) |
| 25 LTS | linux-lts | Fixed (6.12.111-r0) | |
| Stream | linux-lts | Fixed (6.18.53-r0) |
References
- https://git.kernel.org/stable/c/3ca3da5c305caa873ddb81e8c6b118143f6dd3d1
- https://git.kernel.org/stable/c/6f815c2fb6ab20385f81c353cdad0ea3b88132af
- https://git.kernel.org/stable/c/7677eb2cbf2cc7446de474c01a6b06277c0051e5
- https://git.kernel.org/stable/c/8d85498016a5bb56339734a14c276209fa65bafc
- https://git.kernel.org/stable/c/d989e22ae9802c52c56ad4284d0caf26696cf6ae
- https://git.kernel.org/stable/c/e3b9aa0773abd5d4ed90be41ce5306c146d5b09e
- https://git.kernel.org/stable/c/fcafb2b1430824bae4258c01a439ec97ca0c6973
- https://git.kernel.org/stable/c/fd8396cfecbd904468c71362f08aaa25f96d5337