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video: fbdev: kyro: Error out if 'lineclock' equals zero

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The userspace program could pass any values to the driver through
ioctl() interface. If the driver doesn't check the value of 'lineclock',
it may cause divide error.

Fix this by checking whether 'lineclock' is zero.

The following log reveals it:
 divide error: 0000 [#1] PREEMPT SMP KASAN PTI
 RIP: 0010:kyrofb_set_par+0x30d/0xd80
 Call Trace:
  <TASK>
  fb_set_var+0x604/0xeb0
  do_fb_ioctl+0x234/0x670
  fb_ioctl+0xdd/0x130
  do_syscall_64+0x3b/0x90

Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Zheyu Ma 2022-04-04 16:47:19 +08:00 committed by Helge Deller
parent 85ec038b53
commit 213e2df473
1 changed files with 2 additions and 0 deletions
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2
drivers/video/fbdev/kyro/fbdev.c
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@ -494,6 +494,8 @@ static int kyrofb_set_par(struct fb_info *info)
info->var.hsync_len +
info->var.left_margin)) / 1000;
if (!lineclock)
return -EINVAL;
/* time for a frame in ns (precision in 32bpp) */
frameclock = lineclock * (info->var.yres +