On 28/11/17 09:29 AM, Dan Carpenter wrote:
> Hello Tom St Denis,
>
> The patch c5a60ce81b49: "drm/amd/amdgpu: Add debugfs support for
> reading GPRs (v2)" from Dec 5, 2016, leads to the following static
> checker warning:
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c:3774 amdgpu_debugfs_gpr_read()
> error: buffer overflow 'data' 1024 <= 4095
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> 3731 static ssize_t amdgpu_debugfs_gpr_read(struct file *f, char __user *buf,
> 3732 size_t size, loff_t *pos)
> 3733 {
> 3734 struct amdgpu_device *adev = f->f_inode->i_private;
> 3735 int r;
> 3736 ssize_t result = 0;
> 3737 uint32_t offset, se, sh, cu, wave, simd, thread, bank, *data;
> 3738
> 3739 if (size & 3 || *pos & 3)
> 3740 return -EINVAL;
> 3741
> 3742 /* decode offset */
> 3743 offset = *pos & GENMASK_ULL(11, 0);
> ^^^^^^
> offset is set to 0-4095.
>
> 3744 se = (*pos & GENMASK_ULL(19, 12)) >> 12;
> 3745 sh = (*pos & GENMASK_ULL(27, 20)) >> 20;
> 3746 cu = (*pos & GENMASK_ULL(35, 28)) >> 28;
> 3747 wave = (*pos & GENMASK_ULL(43, 36)) >> 36;
> 3748 simd = (*pos & GENMASK_ULL(51, 44)) >> 44;
> 3749 thread = (*pos & GENMASK_ULL(59, 52)) >> 52;
> 3750 bank = (*pos & GENMASK_ULL(61, 60)) >> 60;
> 3751
> 3752 data = kmalloc_array(1024, sizeof(*data), GFP_KERNEL);
> ^^^^
> data is a 1024 element array
>
> 3753 if (!data)
> 3754 return -ENOMEM;
> 3755
> 3756 /* switch to the specific se/sh/cu */
> 3757 mutex_lock(&adev->grbm_idx_mutex);
> 3758 amdgpu_gfx_select_se_sh(adev, se, sh, cu);
> 3759
> 3760 if (bank == 0) {
> 3761 if (adev->gfx.funcs->read_wave_vgprs)
> 3762 adev->gfx.funcs->read_wave_vgprs(adev, simd, wave, thread, offset, size>>2, data);
> 3763 } else {
> 3764 if (adev->gfx.funcs->read_wave_sgprs)
> 3765 adev->gfx.funcs->read_wave_sgprs(adev, simd, wave, offset, size>>2, data);
> 3766 }
> 3767
> 3768 amdgpu_gfx_select_se_sh(adev, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF);
> 3769 mutex_unlock(&adev->grbm_idx_mutex);
> 3770
> 3771 while (size) {
> 3772 uint32_t value;
> 3773
> 3774 value = data[offset++];
> ^^^^^^^^^^^^^^
> We're possibly reading beyond the end of the array. Maybe we are
> supposed to divide the offset /= sizeof(*data)?
Hi Dan,
umr only reads from offset zero but to be consistent I think yes the
offset should be /= 4 first since we ensure it's 4 byte aligned it's
clearly a 4 byte offset.
Thanks for finding this, I'll craft up a patch shortly.
Cheers,
Tom
