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

From: Arnd Bergmann
Date: Mon Sep 27 2021 - 07:37:09 EST


From: Arnd Bergmann <arnd@xxxxxxxx>

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@xxxxxxxx>
---
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