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From: Ingo Molnar <mingo@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linuxfoundation.org>,
	x86@kernel.org, Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Borislav Petkov <bp@alien8.de>,
	Dominik Brodowski <linux@dominikbrodowski.net>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [patch 1/3] x86/ldt: Free the right LDT memory in write_ldt() error path
Date: Sat, 30 Dec 2017 22:33:37 +0100	[thread overview]
Message-ID: <20171230213337.tns3dtj7z526bvf2@gmail.com> (raw)
In-Reply-To: <20171230211829.508293470@linutronix.de>


* Thomas Gleixner <tglx@linutronix.de> wrote:

> The error path in write_ldt() frees the already installed LDT memory
> instead of the newly allocated which cannot be installed.

s/newly allocated
 /newly allocated one

> 
> Fixes: f55f0501cbf6 ("x86/pti: Put the LDT in its own PGD if PTI is on")
> Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
>  arch/x86/kernel/ldt.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> --- a/arch/x86/kernel/ldt.c
> +++ b/arch/x86/kernel/ldt.c
> @@ -421,7 +421,7 @@ static int write_ldt(void __user *ptr, u
>  	 */
>  	error = map_ldt_struct(mm, new_ldt, old_ldt ? !old_ldt->slot : 0);
>  	if (error) {
> -		free_ldt_struct(old_ldt);
> +		free_ldt_struct(new_ldt);
>  		goto out_unlock;
>  	}
>  

This bug kind of scares me ...

Reviewed-by: Ingo Molnar <mingo@kernel.org>

Thanks,

	Ingo

  reply	other threads:[~2017-12-30 21:33 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-30 21:13 [patch 0/3] x86/pti: Fix various fallout Thomas Gleixner
2017-12-30 21:13 ` [patch 1/3] x86/ldt: Free the right LDT memory in write_ldt() error path Thomas Gleixner
2017-12-30 21:33   ` Ingo Molnar [this message]
2017-12-31 10:24   ` [patch V2 1/3] x86/ldt: Plug memory leak in " Thomas Gleixner
2017-12-31 15:23     ` Andy Lutomirski
2017-12-30 21:13 ` [patch 2/3] x86/smpboot: Remove stale tlb flush invocations Thomas Gleixner
2017-12-30 21:32   ` Ingo Molnar
2017-12-30 21:13 ` [patch 3/3] x86/mm: Remove preempt_disable/enable() from __native_flush_tlb() Thomas Gleixner
2017-12-30 21:31   ` Ingo Molnar
2017-12-30 21:35 ` [patch 0/3] x86/pti: Fix various fallout Ingo Molnar
2017-12-30 22:06   ` Linus Torvalds
2017-12-31  2:23     ` Andy Lutomirski

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