Re: [PATCH] drm/amdgpu: Use kvfree instead of kfree in amdgpu_gmc_get_nps_memranges()

[Alex Deucher]

On Thu, Jan 29, 2026 at 5:12 AM Lazar, Lijo <lijo.lazar@xxxxxxx> wrote:
>
>
>
> On 29-Jan-26 3:00 PM, Christian König wrote:
> > On 1/29/26 10:05, Zilin Guan wrote:
> >> amdgpu_discovery_get_nps_info() internally allocates memory for ranges
> >> using kvcalloc(), which may use vmalloc() for large allocation. Using
> >> kfree() to release vmalloc memory will lead to a memory corruption.
> >>
> >> Use kvfree() to safely handle both kmalloc and vmalloc allocations.
> >>
> >> Compile tested only. Issue found using a prototype static analysis tool
> >> and code review.
> >>
> >> Fixes: b194d21b9bcc ("drm/amdgpu: Use NPS ranges from discovery table")
> >> Signed-off-by: Zilin Guan <zilin@xxxxxxxxxx>
> >
> > Good catch!
> >
> > But i think we rather need to question why amdgpu_discovery_get_nps_info() is using kvcalloc()? I have strong doubts that we need vmalloc() here.
> >
>
> Yes, vmalloc is enough. That change can be made separately or modified
> along with this.
>
> As for this as a standalone change -
>         Reviewed-by: Lijo Lazar <lijo.lazar@xxxxxxx>

Applied.  Thanks!

Alex

>
> Thanks,
> Lijo
>
>
> > Regards,
> > Christian.
> >
> >> ---
> >>   drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c | 2 +-
> >>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> >> index 7e623f91f2d7..cb0d1ac148e9 100644
> >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.c
> >> @@ -1382,7 +1382,7 @@ int amdgpu_gmc_get_nps_memranges(struct amdgpu_device *adev,
> >>      if (!*exp_ranges)
> >>              *exp_ranges = range_cnt;
> >>   err:
> >> -    kfree(ranges);
> >> +    kvfree(ranges);
> >>
> >>      return ret;
> >>   }
> >
>