linux-kernel - [PATCH] x86: simplefb: avoid overflow

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Message-Id: <1378459933-367-1-git-send-email-teg@jklm.no>
Date:	Fri,  6 Sep 2013 11:32:13 +0200
From:	Tom Gundersen <teg@...m.no>
To:	x86@...nel.org
Cc:	linux-kernel@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
	Tom Gundersen <teg@...m.no>,
	David Herrmann <dh.herrmann@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH] x86: simplefb: avoid overflow

lfb_size can easily be say 4M, which would make the bitshit overflow and
the test fail.

Signed-off-by: Tom Gundersen <teg@...m.no>
Cc: David Herrmann <dh.herrmann@...il.com>
Cc: H. Peter Anvin <hpa@...or.com>
---
 arch/x86/kernel/sysfb_simplefb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/sysfb_simplefb.c b/arch/x86/kernel/sysfb_simplefb.c
index 22513e9..fff44a5 100644
--- a/arch/x86/kernel/sysfb_simplefb.c
+++ b/arch/x86/kernel/sysfb_simplefb.c
@@ -72,7 +72,7 @@ __init int create_simplefb(const struct screen_info *si,
 	 * the part that is occupied by the framebuffer */
 	len = mode->height * mode->stride;
 	len = PAGE_ALIGN(len);
-	if (len > si->lfb_size << 16) {
+	if (len > ((unsigned long) si->lfb_size) << 16) {
 		printk(KERN_WARNING "sysfb: VRAM smaller than advertised\n");
 		return -EINVAL;
 	}
-- 
1.8.4

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