Re: [PATCH 4/7] x86/dumpstack: If addr_limit is non-default, display it

From: Borislav Petkov <bp@alien8.de>
To: Andy Lutomirski <luto@kernel.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
	Kees Cook <keescook@chromium.org>,
	Brian Gerst <brgerst@gmail.com>
Subject: Re: [PATCH 4/7] x86/dumpstack: If addr_limit is non-default, display it
Date: Wed, 25 May 2016 13:32:40 +0200	[thread overview]
Message-ID: <20160525113240.GB4420@pd.tnic> (raw)
In-Reply-To: <be65c2feeaed23b29fbe92c24088a1aa793fe999.1464129798.git.luto@kernel.org>

On Tue, May 24, 2016 at 03:48:41PM -0700, Andy Lutomirski wrote:
> This will help debug OOPSes related to USER_DS vs KERNEL_DS.
> 
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
>  arch/x86/kernel/dumpstack_32.c | 4 ++++
>  arch/x86/kernel/dumpstack_64.c | 5 +++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
> index 464ffd69b92e..5dbb08fd8291 100644
> --- a/arch/x86/kernel/dumpstack_32.c
> +++ b/arch/x86/kernel/dumpstack_32.c
> @@ -124,8 +124,12 @@ show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
>  void show_regs(struct pt_regs *regs)
>  {
>  	int i;
> +	struct thread_info *ti = current_thread_info();
>  
>  	show_regs_print_info(KERN_EMERG);
> +	if (ti->addr_limit.seg != TASK_SIZE_MAX)
> +		printk(KERN_DEFAULT "task.addr_limit: 0x%lx\n",
> +		       ti->addr_limit.seg);

I guess we can dump that unconditionally just to be consistent and so
that all oopses look the same, i.e., with that line always present.

-- 
Regards/Gruss,
    Boris.

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