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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: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
This commit is contained in:
Zheyu Ma 2022-04-04 16:47:21 +08:00 committed by Helge Deller
parent f2bfd792c1
commit 16844e5870
1 changed files with 3 additions and 0 deletions
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3
drivers/video/fbdev/tridentfb.c
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@ -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;