linux-kernel - [PATCH v2] misc: fastrpc: Use memdup

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Date: Wed,  8 May 2024 00:22:27 +0200
From: Thorsten Blum <thorsten.blum@...lux.com>
To: arnd@...db.de
Cc: amahesh@....qualcomm.com,
	gregkh@...uxfoundation.org,
	linux-arm-msm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	srinivas.kandagatla@...aro.org,
	thorsten.blum@...lux.com
Subject: [PATCH v2] misc: fastrpc: Use memdup_user()

Switching to memdup_user() overwrites the allocated memory only once,
whereas kzalloc() followed by copy_from_user() initializes the allocated
memory to zero and then immediately overwrites it.

Fixes the following Coccinelle/coccicheck warning reported by
memdup_user.cocci:

	WARNING opportunity for memdup_user

Signed-off-by: Thorsten Blum <thorsten.blum@...lux.com>
Acked-by: Arnd Bergmann <arnd@...db.de>
---
Changes in v2:
- Use u64_to_user_ptr() as suggested by Arnd Bergmann (thanks!)
- Preserve Acked-by: tag
---
 drivers/misc/fastrpc.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 4c67e2c5a82e..694fc083b1bd 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -1259,17 +1259,12 @@ static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
 		goto err;
 	}
 
-	name = kzalloc(init.namelen, GFP_KERNEL);
-	if (!name) {
-		err = -ENOMEM;
+	name = memdup_user(u64_to_user_ptr(init.name), init.namelen);
+	if (IS_ERR(name)) {
+		err = PTR_ERR(name);
 		goto err;
 	}
 
-	if (copy_from_user(name, (void __user *)(uintptr_t)init.name, init.namelen)) {
-		err = -EFAULT;
-		goto err_name;
-	}
-
 	if (!fl->cctx->remote_heap) {
 		err = fastrpc_remote_heap_alloc(fl, fl->sctx->dev, init.memlen,
 						&fl->cctx->remote_heap);
-- 
2.45.0