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

[Lazar, Lijo]

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 <zi...@seu.edu.cn>

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.la...@amd.com>

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;
  }