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Date: Fri, 8 Jul 2011 11:42:38 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: drosenberg@vsecurity.com
Cc: chris@zankel.net, security@kernel.org, linux-kernel@vger.kernel.org,
        "Oleg Nesterov" <oleg@redhat.com>
Subject: Re: [Security] [PATCH] xtensa: prevent arbitrary read in ptrace
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On Fri, 8 Jul 2011 18:35:56 +0000
"Dan Rosenberg" <drosenberg@vsecurity.com> wrote:

> Sorry for the top post and any email mangling (mobile).
> 
> I only used EIO to mirror the existing behavior in ptrace_getxregs(). EFAULT seems better.

ptrace_getxregs() is busted ;)


int ptrace_getxregs(struct task_struct *child, void __user *uregs)
{
...
	if (!access_ok(VERIFY_WRITE, uregs, sizeof(elf_xtregs_t)))
		return -EIO;
...
	ret |= __copy_to_user(&xtregs->user,&ti->xtregs_user,
			      sizeof(xtregs->user));

	return ret ? -EFAULT : 0;
}

that makes no sense.