From: Andrew Morton <akpm@linux-foundation.org>
To: Anastasia Belova <abelova@astralinux.ru>
Cc: Max Filippov <jcmvbkbc@gmail.com>, Ingo Molnar <mingo@kernel.org>,
Vineet Gupta <vgupta@kernel.org>,
"Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
Geert Uytterhoeven <geert@linux-m68k.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
lvc-project@linuxtesting.org
Subject: Re: [PATCH] mm: Add check for NULL for unlocked in fixup_user_fault
Date: Thu, 15 Dec 2022 13:22:36 -0800 [thread overview]
Message-ID: <20221215132236.195e6f3ac1e1cc4e9e012c8f@linux-foundation.org> (raw)
In-Reply-To: <20221215093930.22026-1-abelova@astralinux.ru>
On Thu, 15 Dec 2022 12:39:30 +0300 Anastasia Belova <abelova@astralinux.ru> wrote:
> Check unlocked for NULL before dereference.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> ...
>
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1282,7 +1282,8 @@ int fixup_user_fault(struct mm_struct *mm,
> * could tell the callers so they do not need to unlock.
> */
> mmap_read_lock(mm);
> - *unlocked = true;
> + if (unlocked)
> + *unlocked = true;
> return 0;
> }
I don't believe this is necessary unless the caller passed
FAULT_FLAG_KILLABLE or FAULT_FLAG_ALLOW_RETRY in fault_flags.
It's clear as mud and some code comments would help.
parent reply other threads:[~2022-12-15 21:22 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20221215093930.22026-1-abelova@astralinux.ru>]
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