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Date: Tue, 2 Jun 2026 12:42:55 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Qing Wang <wangqing7171@gmail.com>
Cc: mathieu.desnoyers@efficios.com, dvyukov@google.com,
	justinstitt@google.com, linux-kernel@vger.kernel.org,
	llvm@lists.linux.dev, mark.rutland@arm.com, mingo@kernel.org,
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	syzbot+185a631927096f9da2fc@syzkaller.appspotmail.com,
	tglx@kernel.org
Subject: Re: [PATCH v2] rseq: fix using an uninitialized stack variable in
 rseq_exit_user_update
Message-ID: <20260602104255.GG4149641@noisy.programming.kicks-ass.net>
References: <20260601143934.GT3493090@noisy.programming.kicks-ass.net>
 <20260602030854.574038-1-wangqing7171@gmail.com>
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In-Reply-To: <20260602030854.574038-1-wangqing7171@gmail.com>

On Tue, Jun 02, 2026 at 11:08:54AM +0800, Qing Wang wrote:
> There is an bug which is an uninitialized stack variable use in
> `rseq_exit_user_update()` reported by syzbot:
> 
> BUG: KMSAN: kernel-infoleak in rseq_set_ids_get_csaddr include/linux/rseq_entry.h:502 [inline]
> 
> The local variable:
> ```c
> 	struct rseq_ids ids = {
> 		.cpu_id	 = task_cpu(t),
> 		.mm_cid	 = task_mm_cid(t),
> 		.node_id = cpu_to_node(ids.cpu_id),
> 	};
> ```

FWIW, I've no idea what that ``` nonsense is, but it does not belong in
Changelogs. I've removed it.