Threats Tagged 'cve-2026-53243'

A vulnerability in the Linux kernel's rseq subsystem involves the use of an uninitialized stack variable in the function rseq_exit_user_update(). This occurs due to the indeterminate evaluation order of expressions in a structure initializer, causing the node_id field to be set before cpu_id is initialized. The issue was identified by syzbot and results in a kernel information leak detected by KMSAN. The vulnerability has been fixed by moving the assignment of the node_id field outside the structure initialization.

In the Linux kernel, the following vulnerability has been resolved: rseq: Fix using an uninitialized stack variable in rseq_exit_user_update() There is an bug in which an uninitialized stack variable is used in rseq_exit_user_update() as reported by syzbot: BUG: KMSAN: kernel-infoleak in rseq_set_ids_get_csaddr include/linux/rseq_entry.h:502 [inline] The local variable: struct rseq_ids ids = { .cpu_id = task_cpu(t), .mm_cid = task_mm_cid(t), .node_id = cpu_to_node(ids.cpu_id), }; According to the C standard, the evaluation order of expressions in an initializer list is indeterminately sequenced. The compiler (Clang, in this KMSAN build) evaluates `cpu_to_node(ids.cpu_id)` *before* `ids.cpu_id` is initialized with `task_cpu(t)`. This is fixed by moving the assignment of ids.node_id outside the structure initialization.