CVE-2026-80851

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CVE-2026-80851

Summary: gtp: serialize PDP context updates

Details: In the Linux kernel, the following vulnerability has been resolved: gtp: serialize PDP context updates PDP contexts can be deleted through GTP_CMD_DELPDP or while the GTP network device is being unregistered. The latter is serialized by RTNL, but the generic-netlink delete path only holds RCU. Running both paths concurrently can therefore make both paths delete the same PDP context. The issue was found through static analysis and reproduced on a KASAN-enabled kernel by a simple two-thread program racing GTP_CMD_DELPDP against RTM_DELLINK: Oops: general protection fault, probably for non-canonical address KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127] RIP: gtp_genl_del_pdp+0x1c1/0x420 [gtp] RBP: dead000000000122 The second deletion dereferenced the poisoned hlist pprev pointer. Serialize gtp_pdp_add(), gtp_genl_del_pdp(), and gtp_dellink() with a shared mutex. Keep the mutex held until the final use of a PDP context in the NEWPDP path, and keep the RCU read-side section around the complete PDP context use in the DELPDP path.

References: https://git.kernel.org/stable/c/1e995498d29784a06a2b2899370a1926cfc8410d, https://git.kernel.org/stable/c/3d950e98f74af9611925a5226edced02155f6ed1, https://git.kernel.org/stable/c/498386b6d402737db1e2eeed4c385acbf0ef9e34, https://git.kernel.org/stable/c/5f77ddb2756340c1b05381674ca025d52998005e, https://git.kernel.org/stable/c/6df4f05bc2991467939d7d80b6f7e121559cc3df, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80851.json, https://nvd.nist.gov/vuln/detail/CVE-2026-80851, https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git