linux-kernel - Re: [PATCHv3 01/12] uprobes: split THPs before trying replace them

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: <20170131154442.GA21637@redhat.com>
Date:   Tue, 31 Jan 2017 16:44:42 +0100
From:   Oleg Nesterov <oleg@...hat.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     Andrea Arcangeli <aarcange@...hat.com>,
        Hugh Dickins <hughd@...gle.com>,
        Rik van Riel <riel@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCHv3 01/12] uprobes: split THPs before trying replace them

On 01/29, Kirill A. Shutemov wrote:
>
> For THPs page_check_address() always fails. It leads to endless loop in
> uprobe_write_opcode().
>
> Testcase with huge-tmpfs (not sure if it's possible to trigger this
> uprobe codepath for anon memory):

No, you can't probe the anonymous memory,

> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -300,8 +300,8 @@ int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
>  
>  retry:
>  	/* Read the page with vaddr into memory */
> -	ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &old_page,
> -			&vma, NULL);
> +	ret = get_user_pages_remote(NULL, mm, vaddr, 1,
> +			FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL);
>  	if (ret <= 0)
>  		return ret;

Thanks,

Acked-by: Oleg Nesterov <oleg@...hat.com>