gtp: add synchronize_net() in gtp_newlink() error path to prevent use-after-free

Summary

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().

Timeline

1. Sep 16, 2026, 8:48 AM UTCCVE published
2. Oct 19, 2026, 8:52 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 459aa660eb1d8ce67080da1983bb81d716aa5a69 · fixed in fcafb2b1430824bae4258c01a439ec97ca0c6973; From 459aa660eb1d8ce67080da1983bb81d716aa5a69 · fixed in 3ca3da5c305caa873ddb81e8c6b118143f6dd3d1; From 459aa660eb1d8ce67080da1983bb81d716aa5a69 · fixed in 6f815c2fb6ab20385f81c353cdad0ea3b88132af; From 459aa660eb1d8ce67080da1983bb81d716aa5a69 · fixed in e3b9aa0773abd5d4ed90be41ce5306c146d5b09e; From 459aa660eb1d8ce67080da1983bb81d716aa5a69 · fixed in fd8396cfecbd904468c71362f08aaa25f96d5337; From 459aa660eb1d8ce67080da1983bb81d716aa5a69 · fixed in 7677eb2cbf2cc7446de474c01a6b06277c0051e5; From 459aa660eb1d8ce67080da1983bb81d716aa5a69 · fixed in 8d85498016a5bb56339734a14c276209fa65bafc; From 459aa660eb1d8ce67080da1983bb81d716aa5a69 · fixed in d989e22ae9802c52c56ad4284d0caf26696cf6ae

• Linux Linux

  4.7

• KernelLinux

  From 4.7.0 · fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.13.0 · fixed in 6.18.52; From 6.19.0 · fixed in 7.2.6

References 8