Use-after-free of orphaned AF_UNIX in Ubuntu builds of Linux kernel

Ubuntu Linux 6.8 GA retains the legacy AF_UNIX garbage collector but backports upstream commit 8594d9b85c07 ("af_unix: Don’t call skb_get() for OOB skb"). When orphaned MSG_OOB sockets hit unix_gc(), the garbage collector still calls kfree_skb() as if OOB SKBs held two references; on Ubuntu Linux 6.8 (Noble Numbat) kernel tree, they have only the queue reference, so the buffer is freed while still reachable and subsequent queue walks dereference freed memory, yielding a reliable local privilege escalation (LPE) caused by a use-after-free (UAF). Ubuntu builds that have already taken the new GC stack from commit 4090fa373f0e, and mainline Linux kernels shipping that infrastructure are unaffected because they no longer execute the legacy collector path. This issue affects Ubuntu Linux from 6.8.0-56.58 before 6.8.0-84.84.

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释放后使用

Canonical Ubuntu 安全漏洞

Canonical Ubuntu是英国科能软件（Canonical）公司的一套以桌面应用为主的GNU/Linux操作系统。 Canonical Ubuntu 6.8.0-56.58至6.8.0-84.84之前版本存在安全漏洞，该漏洞源于AF_UNIX垃圾收集器存在释放后重用问题，可能导致可靠的本地权限提升。

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