linux-kernel - Re: [PATCH] drm/amdgpu: avoid out of bounds access on array interrupt_status_offsets

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Message-ID: <57E158B4.7090802@canonical.com>
Date:   Tue, 20 Sep 2016 16:41:40 +0100
From:   Colin Ian King <colin.king@...onical.com>
To:     Alex Deucher <alexdeucher@...il.com>
Cc:     Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        David Airlie <airlied@...ux.ie>,
        Ken Wang <Qingqing.Wang@....com>,
        Maling list - DRI developers 
        <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/amdgpu: avoid out of bounds access on array
 interrupt_status_offsets

On 20/09/16 16:39, Alex Deucher wrote:
> On Tue, Sep 20, 2016 at 11:16 AM, Colin King <colin.king@...onical.com> wrote:
>> From: Colin Ian King <colin.king@...onical.com>
>>
>> The check for an out of bound index into array interrupt_status_offsets
>> is off-by-one. Fix this and also don't compared to a hard coded array
>> size but use ARRAY_SIZE instead.
>>
>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
>> ---
>>  drivers/gpu/drm/amd/amdgpu/dce_v6_0.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/dce_v6_0.c b/drivers/gpu/drm/amd/amdgpu/dce_v6_0.c
>> index d3512f3..4ce4c1a 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/dce_v6_0.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/dce_v6_0.c
>> @@ -2782,7 +2782,7 @@ static int dce_v6_0_hpd_irq(struct amdgpu_device *adev,
>>         uint32_t disp_int, mask, int_control, tmp;
>>         unsigned hpd;
>>
>> -       if (entry->src_data > 6) {
>> +       if (entry->src_data >= ARRAY_SIZE(interrupt_status_offsets)) {
> 
> This should actually be adev->mode_info.num_hpd as some asic variants
> may not have 6 hpd lines.  Thanks for catching this.
> 
> Alex

Ah, that's a better way, so:
	if (entry->src_data >= adev->mode_info.num_hpd) {
	...

I'll send V2

> 
>>                 DRM_DEBUG("Unhandled interrupt: %d %d\n", entry->src_id, entry->src_data);
>>                 return 0;
>>         }
>> --
>> 2.9.3
>>
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>> dri-devel@...ts.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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