Commit 16844e58 authored by Zheyu Ma's avatar Zheyu Ma Committed by Helge Deller
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video: fbdev: tridentfb: Error out if 'pixclock' equals zero 



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

Fix this by checking whether 'pixclock' is zero.

The following log reveals it:
 divide error: 0000 [#1] PREEMPT SMP KASAN PTI
 RIP: 0010:tridentfb_check_var+0x853/0xe60
 Call Trace:
  <TASK>
  fb_set_var+0x367/0xeb0
  do_fb_ioctl+0x234/0x670
  fb_ioctl+0xdd/0x130
  do_syscall_64+0x3b/0x90

Signed-off-by: default avatarZheyu Ma <zheyuma97@gmail.com>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
parent f2bfd792

drivers/video/fbdev/tridentfb.c

+3 −0
Original line number Diff line number Diff line
@@ -996,6 +996,9 @@ static int tridentfb_check_var(struct fb_var_screeninfo *var, 
	int ramdac = 230000; /* 230MHz for most 3D chips */

	debug("enter\n");



	if (!var->pixclock)

		return -EINVAL;



	/* check color depth */

	if (bpp == 24)

		bpp = var->bits_per_pixel = 32;