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fbmon: prevent division by zero in fb_videomode_from_videomode()

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The expression htotal * vtotal can have a zero value on
overflow. It is necessary to prevent division by zero like in
fb_var_to_videomode().

Found by Linux Verification Center (linuxtesting.org) with Svace.

Signed-off-by: Roman Smirnov <r.smirnov@omp.ru>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Roman Smirnov 2024-03-19 11:13:44 +03:00 committed by Helge Deller
parent 152609795d
commit c2d953276b
1 changed files with 4 additions and 3 deletions
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7
drivers/video/fbdev/core/fbmon.c
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@ -1311,7 +1311,7 @@ int fb_get_mode(int flags, u32 val, struct fb_var_screeninfo *var, struct fb_inf
int fb_videomode_from_videomode(const struct videomode *vm,
struct fb_videomode *fbmode)
{
unsigned int htotal, vtotal;
unsigned int htotal, vtotal, total;
fbmode->xres = vm->hactive;
fbmode->left_margin = vm->hback_porch;
@ -1344,8 +1344,9 @@ int fb_videomode_from_videomode(const struct videomode *vm,
vtotal = vm->vactive + vm->vfront_porch + vm->vback_porch +
vm->vsync_len;
/* prevent division by zero */
if (htotal && vtotal) {
fbmode->refresh = vm->pixelclock / (htotal * vtotal);
total = htotal * vtotal;
if (total) {
fbmode->refresh = vm->pixelclock / total;
/* a mode must have htotal and vtotal != 0 or it is invalid */
} else {
fbmode->refresh = 0;