[AMD Official Use Only - General]
-----Original Message-----
From: Koenig, Christian <Christian.Koenig@xxxxxxx>
Sent: Thursday, April 25, 2024 9:31 PM
To: Alex Deucher <alexdeucher@xxxxxxxxx>; Huang, Tim <Tim.Huang@xxxxxxx>
Cc: amd-gfx@xxxxxxxxxxxxxxxxxxxxx; Deucher, Alexander <Alexander.Deucher@xxxxxxx>
Subject: Re: [PATCH v2] drm/amdgpu: fix overflowed array index read warning
Am 25.04.24 um 15:28 schrieb Alex Deucher:
> On Thu, Apr 25, 2024 at 3:22 AM Tim Huang <tim.huang@xxxxxxx> wrote:
>> From: Tim Huang <Tim.Huang@xxxxxxx>
>>
>> Clear warning that cast operation might have overflowed.
>>
>> v2: keep reverse xmas tree order to declare "int r;" (Christian)
>>
>> Signed-off-by: Tim Huang <Tim.Huang@xxxxxxx>
>> ---
>> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>> index 06f0a6534a94..8cf60acb2970 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
>> @@ -473,8 +473,8 @@ static ssize_t amdgpu_debugfs_ring_read(struct file *f, char __user *buf,
>> size_t size, loff_t *pos)
>> {
>> struct amdgpu_ring *ring = file_inode(f)->i_private;
>> - int r, i;
>> uint32_t value, result, early[3];
>> + int r;
>>
>> if (*pos & 3 || size & 3)
>> return -EINVAL;
>> @@ -485,7 +485,7 @@ static ssize_t amdgpu_debugfs_ring_read(struct file *f, char __user *buf,
>> early[0] = amdgpu_ring_get_rptr(ring) & ring->buf_mask;
>> early[1] = amdgpu_ring_get_wptr(ring) & ring->buf_mask;
>> early[2] = ring->wptr & ring->buf_mask;
>> - for (i = *pos / 4; i < 3 && size; i++) {
>> + for (loff_t i = *pos / 4; i < 3 && size; i++) {
> Some older compilers complain about declarations mixed with code like
> this. Not sure how big a deal that would be.
>Good point, we would like to be able to backport this.
>Somebody from Alivins team needs to comment, but IIRC we agreed that this would be legal and we take care of it by using appropriate compiler flags on older kernels.
>Christian.
Thanks for pointing out. Will avoid doing this.
>
> Alex
>
>> r = put_user(early[i], (uint32_t *)buf);
>> if (r)
>> return r;
>> --
>> 2.39.2
>>
