linux-kernel - [PATCH] staging: vc04_services: shut up out-of-range warning

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Message-Id: <20210927113702.3866843-1-arnd@kernel.org>
Date:   Mon, 27 Sep 2021 13:36:56 +0200
From:   Arnd Bergmann <arnd@...nel.org>
To:     Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Ojaswin Mujoo <ojaswin98@...il.com>,
        Phil Elwell <phil@...pberrypi.com>,
        Amarjargal Gundjalam <amarjargal16@...il.com>,
        bcm-kernel-feedback-list@...adcom.com,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-staging@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH] staging: vc04_services: shut up out-of-range warning

From: Arnd Bergmann <arnd@...db.de>

The comparison against SIZE_MAX produces a harmless warning on 64-bit
architectures:

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:185:16: error: result of comparison of constant 419244183493398898 with expression of type 'unsigned int' is always false [-Werror,-Wtautological-constant-out-of-range-compare]
        if (num_pages > (SIZE_MAX - sizeof(struct pagelist) -
            ~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Shut up that warning by adding a cast to a longer type.

Fixes: ca641bae6da9 ("staging: vc04_services: prevent integer overflow in create_pagelist()")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
index b25369a13452..967f10b9582a 100644
--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c
@@ -182,7 +182,7 @@ create_pagelist(char *buf, char __user *ubuf,
 		offset = (uintptr_t)ubuf & (PAGE_SIZE - 1);
 	num_pages = DIV_ROUND_UP(count + offset, PAGE_SIZE);
 
-	if (num_pages > (SIZE_MAX - sizeof(struct pagelist) -
+	if ((size_t)num_pages > (SIZE_MAX - sizeof(struct pagelist) -
 			 sizeof(struct vchiq_pagelist_info)) /
 			(sizeof(u32) + sizeof(pages[0]) +
 			 sizeof(struct scatterlist)))
-- 
2.29.2