linux-kernel - Re: [PATCH v3 0/4] Add overflow checks for several syscalls

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Message-ID: <0b193743-b3ad-6e05-f6bb-ae5653fd5ef0@redhat.com>
Date:   Fri, 3 Feb 2023 18:10:24 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Wupeng Ma <mawupeng1@...wei.com>, akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        kuleshovmail@...il.com, aneesh.kumar@...ux.ibm.com
Subject: Re: [PATCH v3 0/4] Add overflow checks for several syscalls

On 28.01.23 07:32, Wupeng Ma wrote:
> From: Ma Wupeng <mawupeng1@...wei.com>
> 
> While testing mlock, we have a problem if the len of mlock is ULONG_MAX.
> The return value of mlock is zero. But nothing will be locked since the
> len in do_mlock overflows to zero due to the following code in mlock:
> 
>    len = PAGE_ALIGN(len + (offset_in_page(start)));
> 
> The same problem happens in munlock.
> 
> Add new check and return -EINVAL to fix this overflowing scenarios since
> they are absolutely wrong.
> 
> Similar logic is used to fix problems with multiple syscalls.
> 
> Changelog since v2[2]:
> - modified the way of checking overflows based on Andrew's comments
> 
> Changelog since v1[1]:
> - only check overflow rather than access_ok to keep backward-compatibility

Do you have some test cases and could we add them to LTP, for example?

-- 
Thanks,

David / dhildenb