linux-kernel - [PATCH] pds_fwctl: Replace kzalloc + copy_from_user with memdup_user in pdsfc_fw

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Message-ID: <20250917150941.168887-1-thorsten.blum@linux.dev>
Date: Wed, 17 Sep 2025 17:09:41 +0200
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: Brett Creeley <brett.creeley@....com>,
	Dave Jiang <dave.jiang@...el.com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Saeed Mahameed <saeedm@...dia.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>
Cc: Thorsten Blum <thorsten.blum@...ux.dev>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] pds_fwctl: Replace kzalloc + copy_from_user with memdup_user in pdsfc_fw_rpc

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

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

No functional changes intended.

Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
---
 drivers/fwctl/pds/main.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/drivers/fwctl/pds/main.c b/drivers/fwctl/pds/main.c
index 9b9d1f6b5556..04d84f892fb8 100644
--- a/drivers/fwctl/pds/main.c
+++ b/drivers/fwctl/pds/main.c
@@ -6,6 +6,7 @@
 #include <linux/pci.h>
 #include <linux/vmalloc.h>
 #include <linux/bitfield.h>
+#include <linux/string.h>
 
 #include <uapi/fwctl/fwctl.h>
 #include <uapi/fwctl/pds.h>
@@ -366,18 +367,10 @@ static void *pdsfc_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
 		return ERR_PTR(err);
 
 	if (rpc->in.len > 0) {
-		in_payload = kzalloc(rpc->in.len, GFP_KERNEL);
-		if (!in_payload) {
-			dev_err(dev, "Failed to allocate in_payload\n");
-			err = -ENOMEM;
-			goto err_out;
-		}
-
-		if (copy_from_user(in_payload, u64_to_user_ptr(rpc->in.payload),
-				   rpc->in.len)) {
+		in_payload = memdup_user(u64_to_user_ptr(rpc->in.payload), rpc->in.len);
+		if (IS_ERR(in_payload)) {
 			dev_dbg(dev, "Failed to copy in_payload from user\n");
-			err = -EFAULT;
-			goto err_in_payload;
+			return in_payload;
 		}
 
 		in_payload_dma_addr = dma_map_single(dev->parent, in_payload,
@@ -453,7 +446,6 @@ static void *pdsfc_fw_rpc(struct fwctl_uctx *uctx, enum fwctl_rpc_scope scope,
 				 rpc->in.len, DMA_TO_DEVICE);
 err_in_payload:
 	kfree(in_payload);
-err_out:
 	if (err)
 		return ERR_PTR(err);
 
-- 
2.51.0