linux-kernel - [PATCH] drm/amdkfd: Replace kzalloc + copy_from_user with memdup

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Message-ID: <20250908213156.565861-2-thorsten.blum@linux.dev>
Date: Mon,  8 Sep 2025 23:31:56 +0200
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: Felix Kuehling <Felix.Kuehling@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Christian König <christian.koenig@....com>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>
Cc: Thorsten Blum <thorsten.blum@...ux.dev>,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] drm/amdkfd: Replace kzalloc + copy_from_user with memdup_user

Replace kzalloc() followed by copy_from_user() with memdup_user() to
improve and simplify kfd_ioctl_set_cu_mask().

Return early if an error occurs and remove the obsolete 'out' label.

No functional changes intended.

Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
---
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index 828a9ceef1e7..5d58a7bf309a 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -521,15 +521,10 @@ static int kfd_ioctl_set_cu_mask(struct file *filp, struct kfd_process *p,
 		cu_mask_size = sizeof(uint32_t) * (max_num_cus/32);
 	}
 
-	minfo.cu_mask.ptr = kzalloc(cu_mask_size, GFP_KERNEL);
-	if (!minfo.cu_mask.ptr)
-		return -ENOMEM;
-
-	retval = copy_from_user(minfo.cu_mask.ptr, cu_mask_ptr, cu_mask_size);
-	if (retval) {
+	minfo.cu_mask.ptr = memdup_user(cu_mask_ptr, cu_mask_size);
+	if (IS_ERR(minfo.cu_mask.ptr)) {
 		pr_debug("Could not copy CU mask from userspace");
-		retval = -EFAULT;
-		goto out;
+		return PTR_ERR(minfo.cu_mask.ptr);
 	}
 
 	mutex_lock(&p->mutex);
@@ -538,7 +533,6 @@ static int kfd_ioctl_set_cu_mask(struct file *filp, struct kfd_process *p,
 
 	mutex_unlock(&p->mutex);
 
-out:
 	kfree(minfo.cu_mask.ptr);
 	return retval;
 }
-- 
2.51.0