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From: Arnd Bergmann <arnd@kernel.org>
To: Nicolas Saenz Julienne <nsaenz@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Dan Carpenter <dan.carpenter@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Stefan Wahren <stefan.wahren@i2se.com>,
	Ojaswin Mujoo <ojaswin98@gmail.com>,
	Phil Elwell <phil@raspberrypi.com>,
	Amarjargal Gundjalam <amarjargal16@gmail.com>,
	bcm-kernel-feedback-list@broadcom.com,
	linux-rpi-kernel@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
Subject: [PATCH] staging: vc04_services: shut up out-of-range warning
Date: Mon, 27 Sep 2021 13:36:56 +0200	[thread overview]
Message-ID: <20210927113702.3866843-1-arnd@kernel.org> (raw)

From: Arnd Bergmann <arnd@arndb.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@arndb.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


             reply	other threads:[~2021-09-27 11:37 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-27 11:36 Arnd Bergmann [this message]
2021-09-27 12:26 ` [PATCH] staging: vc04_services: shut up out-of-range warning Dan Carpenter
2021-09-27 13:21   ` Phil Elwell
2021-09-27 20:37     ` Arnd Bergmann

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