From: Jason Gunthorpe <jgg@ziepe.ca>
To: Liu Dalin <liudalin@kylinsec.com.cn>
Cc: Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@kernel.org>,
John Hubbard <jhubbard@nvidia.com>, Peter Xu <peterx@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Liu Dalin <liudalin@kylinsec.com>,
Deng yingchao <dengyingchao@kylinsec.com.cn>,
Qin yungao <qinyungao@kylinsec.com.cn>,
Luo Qiu <luoqiu@kylinsec.com.cn>
Subject: Re: [PATCH] mm/gup: add NULL check for unlocked parameter in fixup_user_fault()
Date: Wed, 26 Aug 2026 11:10:32 -0300 [thread overview]
Message-ID: <20260826141032.GE1449020@ziepe.ca> (raw)
In-Reply-To: <D1CF78FF9DD1C630+20260826062943.3255351-1-liudalin@kylinsec.com.cn>
On Wed, Aug 26, 2026 at 02:29:43PM +0800, Liu Dalin wrote:
> While the current callers either pass a valid pointer or explicitly
> pass NULL (indicating they don't need the unlock notification), it is
> safer to add a defensive NULL check before dereferencing. This prevents
> a kernel crash if any caller passes NULL and handle_mm_fault() returns
> VM_FAULT_COMPLETED or VM_FAULT_RETRY.
>
> Fixes smatch warnings:
> - mm/gup.c:1597 fixup_user_fault() error: we previously assumed 'unlocked' could be null (see line 1573)
It would be better to remove the previous check:
if (unlocked)
fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
And update the kdoc if it is now true that the unlocked parameter
cannot be null
Jason
next prev parent reply other threads:[~2026-08-26 14:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-26 6:29 Liu Dalin
2026-08-26 14:10 ` Jason Gunthorpe [this message]
2026-08-26 6:31 Liu Dalin
2026-08-26 7:49 ` David Hildenbrand (Arm)
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