linux-kernel - Re: [PATCH] mm: page_alloc: validate buddy page before using

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 for Android: free password hash cracker in your pocket

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

Message-ID: <b08725b1-2f4b-cea0-43fc-1ce0a2a7e8f4@linux.alibaba.com>
Date:   Fri, 17 Jun 2022 00:20:19 +0800
From:   Xianting Tian <xianting.tian@...ux.alibaba.com>
To:     akpm@...ux-foundation.org, ziy@...dia.com,
        gregkh@...uxfoundation.org, stable@...r.kernel.org,
        guoren@...nel.org
Cc:     huanyi.xj@...baba-inc.com, guohanjun@...wei.com,
        zjb194813@...baba-inc.com, tianhu.hh@...baba-inc.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: page_alloc: validate buddy page before using

Sorry, please ignore this one.

在 2022/6/17 上午12:17, Xianting Tian 写道:
> Commit 787af64d05cd ("mm: page_alloc: validate buddy before check its migratetype.")
> fixes a bug in 1dd214b8f21c and there is a similar bug in d9dddbf55667 that
> can be fixed in a similar way too.
>
> In addition, for RISC-V arch the first 2MB RAM could be reserved for opensbi,
> so it would have pfn_base=512 and mem_map began with 512th PFN when
> CONFIG_FLATMEM=y.
> But __find_buddy_pfn algorithm thinks the start pfn 0, it could get 0 pfn or
> less than the pfn_base value. We need page_is_buddy() to verify the buddy to
> prevent accessing an invalid buddy.
>
> Fixes: d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and other pageblocks")
> Cc: stable@...r.kernel.org
> Reported-by: zjb194813@...baba-inc.com
> Reported-by: tianhu.hh@...baba-inc.com
> Signed-off-by: Xianting Tian <xianting.tian@...ux.alibaba.com>
> ---
>   mm/page_alloc.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index a6e682569e5b..1c423faa4b62 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -864,6 +864,9 @@ static inline void __free_one_page(struct page *page,
>   
>   			buddy_idx = __find_buddy_index(page_idx, order);
>   			buddy = page + (buddy_idx - page_idx);
> +
> +			if (!page_is_buddy(page, buddy, order))
> +				goto done_merging;
>   			buddy_mt = get_pageblock_migratetype(buddy);
>   
>   			if (migratetype != buddy_mt