linux-kernel - Re: [PATCH 1/2] arm64: hugetlb: remove the wrong pmd check in find_num

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]

Date:   Thu, 3 Nov 2016 18:16:16 -0600
From:   Catalin Marinas <catalin.marinas@....com>
To:     Huang Shijie <shijie.huang@....com>
Cc:     dwoods@...lanox.com, steve.capper@....com, will.deacon@....com,
        linux-kernel@...r.kernel.org, kaly.xin@....com,
        akpm@...ux-foundation.org, nd@....com,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/2] arm64: hugetlb: remove the wrong pmd check in
 find_num_contig()

On Thu, Nov 03, 2016 at 10:27:38AM +0800, Huang Shijie wrote:
> diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
> index 2e49bd2..4811ef1 100644
> --- a/arch/arm64/mm/hugetlbpage.c
> +++ b/arch/arm64/mm/hugetlbpage.c
> @@ -61,10 +61,6 @@ static int find_num_contig(struct mm_struct *mm, unsigned long addr,
>  		return 1;
>  	}
>  	pmd = pmd_offset(pud, addr);
> -	if (!pmd_present(*pmd)) {
> -		VM_BUG_ON(!pmd_present(*pmd));
> -		return 1;
> -	}
>  	if ((pte_t *)pmd == ptep) {
>  		*pgsize = PMD_SIZE;
>  		return CONT_PMDS;

BTW, for the !pud_present() and !pgd_present() cases, shouldn't
find_num_contig() actually return 0? These are more likely real bugs, so
no point in setting the huge pte.

-- 
Catalin