linux-kernel - [PATCH] drm/i915: Replace kmalloc() + copy_from_user() with memdup

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Message-ID: <20250902081046.35463-2-thorsten.blum@linux.dev>
Date: Tue,  2 Sep 2025 10:10:42 +0200
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: Jani Nikula <jani.nikula@...ux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Nitin Gote <nitin.r.gote@...el.com>,
	Mikołaj Wasiak <mikolaj.wasiak@...el.com>,
	Krzysztof Niemiec <krzysztof.niemiec@...el.com>,
	Andi Shyti <andi.shyti@...ux.intel.com>
Cc: Thorsten Blum <thorsten.blum@...ux.dev>,
	Jani Nikula <jani.nikula@...el.com>,
	intel-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] drm/i915: Replace kmalloc() + copy_from_user() with memdup_user()

Replace kmalloc() followed by copy_from_user() with memdup_user() to
improve and simplify set_context_image(), and to silence the following
Coccinelle/coccicheck warning reported by memdup_user.cocci:

  WARNING opportunity for memdup_user

No functional changes intended.

Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
---
Resending this (with updated patch subject and description) because the
CI logs [1] from my first submission [2] about a year ago are no longer
available.

[1] https://patchwork.freedesktop.org/series/139319/
[2] https://lore.kernel.org/lkml/20240925141750.51198-1-thorsten.blum@linux.dev/
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 15835952352e..ed6599694835 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -2158,18 +2158,12 @@ static int set_context_image(struct i915_gem_context *ctx,
 		goto out_ce;
 	}
 
-	state = kmalloc(ce->engine->context_size, GFP_KERNEL);
-	if (!state) {
-		ret = -ENOMEM;
+	state = memdup_user(u64_to_user_ptr(user.image), ce->engine->context_size);
+	if (IS_ERR(state)) {
+		ret = PTR_ERR(state);
 		goto out_ce;
 	}
 
-	if (copy_from_user(state, u64_to_user_ptr(user.image),
-			   ce->engine->context_size)) {
-		ret = -EFAULT;
-		goto out_state;
-	}
-
 	shmem_state = shmem_create_from_data(ce->engine->name,
 					     state, ce->engine->context_size);
 	if (IS_ERR(shmem_state)) {
-- 
2.51.0