linux-kernel - Re: [Bug report] hash_name() may cross page boundary and trigger sleep in RCU context

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251126185545.GC3538@ZenIV>
Date: Wed, 26 Nov 2025 18:55:45 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: Zizhi Wo <wozizhi@...weicloud.com>
Cc: jack@...e.com, brauner@...nel.org, hch@....de,
	akpm@...ux-foundation.org, linux@...linux.org.uk,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, linux-arm-kernel@...ts.infradead.org,
	wozizhi@...wei.com, yangerkun@...wei.com,
	wangkefeng.wang@...wei.com, pangliyuan1@...wei.com,
	xieyuanbin1@...wei.com
Subject: Re: [Bug report] hash_name() may cross page boundary and trigger
 sleep in RCU context

On Wed, Nov 26, 2025 at 05:05:05PM +0800, Zizhi Wo wrote:

> under an RCU read-side critical section. In linux-mainline, arm/arm64
> do_page_fault() still has this problem:
> 
> lock_mm_and_find_vma->get_mmap_lock_carefully->mmap_read_lock_killable.

	arm64 shouldn't hit do_page_fault() in the first place, and
do_translation_fault() there will see that address is beyond TASK_SIZE
and go straight to do_bad_area() -> __do_kernel_fault() -> fixup_exception(),
with no messing with mmap_lock.

	Can anybody confirm that problem exists on arm64 (ideally - with
reproducer)?