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| author |   Zheyu Ma <zheyuma97@gmail.com> | 2021-07-21 12:43:44 +0000 |
|---|---|---|
| committer |   Sam Ravnborg <sam@ravnborg.org> | 2021-07-21 15:02:03 +0200 |
| commit | 030fadb0138186cfa04492e1132a9df514d03841 (patch) | |
| tree | 0e2667417713c49f563150eb8c3582e802b86f93 /drivers/video | |
| parent | video: fbdev: arcfb: remove redundant initialization of variable err (diff) | |
| download | linux-dev-030fadb0138186cfa04492e1132a9df514d03841.tar.xz linux-dev-030fadb0138186cfa04492e1132a9df514d03841.zip | |
video: fbdev: neofb: add a check against divide error
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 because of the 'PICOS2KHZ' macro.
Fix this by checking whether 'pixclock' is zero first.
The following log reveals it:
[ 53.093806] divide error: 0000 [#1] PREEMPT SMP KASAN PTI
[ 53.093838] CPU: 3 PID: 11763 Comm: hang Not tainted 5.14.0-rc2-00478-g2734d6c1b1a0 #215
[ 53.093859] RIP: 0010:neofb_check_var+0x80/0xe50
[ 53.093951] Call Trace:
[ 53.093956] ? neofb_setcolreg+0x2b0/0x2b0
[ 53.093968] fb_set_var+0x2e4/0xeb0
[ 53.093977] ? fb_blank+0x1a0/0x1a0
[ 53.093984] ? lock_acquire+0x1ef/0x530
[ 53.093996] ? lock_release+0x810/0x810
[ 53.094005] ? lock_is_held_type+0x100/0x140
[ 53.094016] ? ___might_sleep+0x1ee/0x2d0
[ 53.094028] ? __mutex_lock+0x620/0x1190
[ 53.094036] ? do_fb_ioctl+0x313/0x700
[ 53.094044] ? mutex_lock_io_nested+0xfa0/0xfa0
[ 53.094051] ? __this_cpu_preempt_check+0x1d/0x30
[ 53.094060] ? _raw_spin_unlock_irqrestore+0x46/0x60
[ 53.094069] ? lockdep_hardirqs_on+0x59/0x100
[ 53.094076] ? _raw_spin_unlock_irqrestore+0x46/0x60
[ 53.094085] ? trace_hardirqs_on+0x6a/0x1c0
[ 53.094096] do_fb_ioctl+0x31e/0x700
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1626871424-27708-1-git-send-email-zheyuma97@gmail.com
Diffstat (limited to 'drivers/video')
| -rw-r--r-- | drivers/video/fbdev/neofb.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/video/fbdev/neofb.c b/drivers/video/fbdev/neofb.c index c0f4f402da3f..966df2a07360 100644 --- a/drivers/video/fbdev/neofb.c +++ b/drivers/video/fbdev/neofb.c @@ -585,7 +585,7 @@ neofb_check_var(struct fb_var_screeninfo *var, struct fb_info *info) DBG("neofb_check_var"); - if (PICOS2KHZ(var->pixclock) > par->maxClock) + if (var->pixclock && PICOS2KHZ(var->pixclock) > par->maxClock) return -EINVAL; /* Is the mode larger than the LCD panel? */ |