diff options
| author | Zheyu Ma <zheyuma97@gmail.com> | 2021-07-26 13:03:53 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-22 12:41:24 +0300 |
| commit | eb7877f282fe15fb6c3751531ab951800a5ffad9 (patch) | |
| tree | 54db19359205500a4577e864505dea1b6b4bb651 | |
| parent | e31ea11dc899092332b8ae52f1787b1dde92f153 (diff) | |
| download | linux-eb7877f282fe15fb6c3751531ab951800a5ffad9.tar.xz | |
video: fbdev: asiliantfb: Error out if 'pixclock' equals zero
[ Upstream commit b36b242d4b8ea178f7fd038965e3cac7f30c3f09 ]
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 first.
The following log reveals it:
[ 43.861711] divide error: 0000 [#1] PREEMPT SMP KASAN PTI
[ 43.861737] CPU: 2 PID: 11764 Comm: i740 Not tainted 5.14.0-rc2-00513-gac532c9bbcfb-dirty #224
[ 43.861756] RIP: 0010:asiliantfb_check_var+0x4e/0x730
[ 43.861843] Call Trace:
[ 43.861848] ? asiliantfb_remove+0x190/0x190
[ 43.861858] fb_set_var+0x2e4/0xeb0
[ 43.861866] ? fb_blank+0x1a0/0x1a0
[ 43.861873] ? lock_acquire+0x1ef/0x530
[ 43.861884] ? lock_release+0x810/0x810
[ 43.861892] ? lock_is_held_type+0x100/0x140
[ 43.861903] ? ___might_sleep+0x1ee/0x2d0
[ 43.861914] ? __mutex_lock+0x620/0x1190
[ 43.861921] ? do_fb_ioctl+0x313/0x700
[ 43.861929] ? mutex_lock_io_nested+0xfa0/0xfa0
[ 43.861936] ? __this_cpu_preempt_check+0x1d/0x30
[ 43.861944] ? _raw_spin_unlock_irqrestore+0x46/0x60
[ 43.861952] ? lockdep_hardirqs_on+0x59/0x100
[ 43.861959] ? _raw_spin_unlock_irqrestore+0x46/0x60
[ 43.861967] ? trace_hardirqs_on+0x6a/0x1c0
[ 43.861978] 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/1627293835-17441-2-git-send-email-zheyuma97@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/video/fbdev/asiliantfb.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/video/fbdev/asiliantfb.c b/drivers/video/fbdev/asiliantfb.c index 7e8ddf00ccc2..dbcc6ebaf904 100644 --- a/drivers/video/fbdev/asiliantfb.c +++ b/drivers/video/fbdev/asiliantfb.c @@ -227,6 +227,9 @@ static int asiliantfb_check_var(struct fb_var_screeninfo *var, { unsigned long Ftarget, ratio, remainder; + if (!var->pixclock) + return -EINVAL; + ratio = 1000000 / var->pixclock; remainder = 1000000 % var->pixclock; Ftarget = 1000000 * ratio + (1000000 * remainder) / var->pixclock; |