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Commit 9027ce4c authored by Sergey Shtylyov's avatar Sergey Shtylyov Committed by Greg Kroah-Hartman
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fbdev: core: fbcvt: avoid division by 0 in fb_cvt_hperiod() 



[ Upstream commit 3f6dae09fc8c306eb70fdfef70726e1f154e173a ]

In fb_find_mode_cvt(), iff mode->refresh somehow happens to be 0x80000000,
cvt.f_refresh will become 0 when multiplying it by 2 due to overflow. It's
then passed to fb_cvt_hperiod(), where it's used as a divider -- division
by 0 will result in kernel oops. Add a sanity check for cvt.f_refresh to
avoid such overflow...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

Fixes: 96fe6a21 ("[PATCH] fbdev: Add VESA Coordinated Video Timings (CVT) support")
Signed-off-by: default avatarSergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 2beee9cf

drivers/video/fbdev/core/fbcvt.c

+1 −1
Original line number Diff line number Diff line
@@ -312,7 +312,7 @@ int fb_find_mode_cvt(struct fb_videomode *mode, int margins, int rb) 
	cvt.f_refresh = cvt.refresh;

	cvt.interlace = 1;



	if (!cvt.xres || !cvt.yres || !cvt.refresh) {

	if (!cvt.xres || !cvt.yres || !cvt.refresh || cvt.f_refresh > INT_MAX) {

		printk(KERN_INFO "fbcvt: Invalid input parameters\n");

		return 1;

	}