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fbdev: core: fbcvt: avoid division by 0 in fb_cvt_hperiod()

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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: 96fe6a2109 ("[PATCH] fbdev: Add VESA Coordinated Video Timings (CVT) support")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Sergey Shtylyov 2025-05-14 23:35:58 +03:00 • committed by Helge Deller
parent cedc1b6339
commit 3f6dae09fc
1 changed files with 1 additions and 1 deletions
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2
drivers/video/fbdev/core/fbcvt.c
View file

@ -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;
}