linux-kernel - Re: [PATCH] dell-wmi: Fix access out of memory

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Date:	Mon, 29 Sep 2014 16:16:23 -0700
From:	Darren Hart <dvhart@...radead.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
CC:	Pali Rohár <pali.rohar@...il.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org
Subject: Re: [PATCH] dell-wmi: Fix access out of memory



On September 29, 2014 4:26:03 PM PDT, "Rafael J. Wysocki" <rjw@...ysocki.net> wrote:
>On Monday, September 29, 2014 02:30:29 PM Darren Hart wrote:
>> On Mon, Sep 29, 2014 at 03:10:51PM +0200, Pali Rohár wrote:
>> > Without this patch driver dell-wmi is trying to access elements of
>dynamically
>> > allocated array without checking array size. This can lead to
>memory corruption
>> > or kernel panic. This patch adds missing checks for array size.
>> > 
>> > Signed-off-by: Pali Rohár <pali.rohar@...il.com>
>> 
>> Looks good to me. Rafael, any concerns?
>
>Not anything obvious.

Queued, thanks.

>
>> 
>> Cc: linux-acpi
>
>Thanks!
>
>
>> > ---
>> > This patch should be probably applied to stable kernel trees as it
>fixing
>> > possible memory corruption.
>> > ---
>> >  drivers/platform/x86/dell-wmi.c |   12 +++++++++---
>> >  1 file changed, 9 insertions(+), 3 deletions(-)
>> > 
>> > diff --git a/drivers/platform/x86/dell-wmi.c
>b/drivers/platform/x86/dell-wmi.c
>> > index 390e8e3..25721bf 100644
>> > --- a/drivers/platform/x86/dell-wmi.c
>> > +++ b/drivers/platform/x86/dell-wmi.c
>> > @@ -163,18 +163,24 @@ static void dell_wmi_notify(u32 value, void
>*context)
>> >  		const struct key_entry *key;
>> >  		int reported_key;
>> >  		u16 *buffer_entry = (u16 *)obj->buffer.pointer;
>> > +		int buffer_size = obj->buffer.length/2;
>> >  
>> > -		if (dell_new_hk_type && (buffer_entry[1] != 0x10)) {
>> > +		if (buffer_size >= 2 && dell_new_hk_type && buffer_entry[1] !=
>0x10) {
>> >  			pr_info("Received unknown WMI event (0x%x)\n",
>> >  				buffer_entry[1]);
>> >  			kfree(obj);
>> >  			return;
>> >  		}
>> >  
>> > -		if (dell_new_hk_type || buffer_entry[1] == 0x0)
>> > +		if (buffer_size >= 3 && (dell_new_hk_type || buffer_entry[1] ==
>0x0))
>> >  			reported_key = (int)buffer_entry[2];
>> > -		else
>> > +		else if (buffer_size >= 2)
>> >  			reported_key = (int)buffer_entry[1] & 0xffff;
>> > +		else {
>> > +			pr_info("Received unknown WMI event\n");
>> > +			kfree(obj);
>> > +			return;
>> > +		}
>> >  
>> >  		key = sparse_keymap_entry_from_scancode(dell_wmi_input_dev,
>> >  							reported_key);
>> 
>> 

-- 
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