linux-kernel - Re: [PATCH] acquire mmap semaphore in pagemap

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, 12 Mar 2009 14:45:33 +0300
From:	Alexey Dobriyan <adobriyan@...il.com>
To:	Martin Schwidefsky <schwidefsky@...ibm.com>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Matt Mackall <mpm@...enic.com>,
	Gerald Schaefer <gerald.schaefer@...ibm.com>,
	akpm@...ux-foundation.org
Subject: Re: [PATCH] acquire mmap semaphore in pagemap_read.

On Thu, Mar 12, 2009 at 11:33:08AM +0100, Martin Schwidefsky wrote:
> --- linux-2.6/fs/proc/task_mmu.c
> +++ linux-2.6-patched/fs/proc/task_mmu.c
> @@ -716,7 +716,9 @@ static ssize_t pagemap_read(struct file 
>  	 * user buffer is tracked in "pm", and the walk
>  	 * will stop when we hit the end of the buffer.
>  	 */
> +	down_read(&mm->mmap_sem);
>  	ret = walk_page_range(start_vaddr, end_vaddr, &pagemap_walk);
> +	up_read(&mm->mmap_sem);

This will introduce "put_user under mmap_sem" which is deadlockable.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/