This is a note to let you know that I've just added the patch titled
video: fbdev: kyro: Error out if 'pixclock' equals zero
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
video-fbdev-kyro-error-out-if-pixclock-equals-zero.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 33b0e792d25c0473a935b1dbc2baeee5706678af
Author: Zheyu Ma <zheyuma97@xxxxxxxxx>
Date: Mon Jul 26 10:03:54 2021 +0000
video: fbdev: kyro: Error out if 'pixclock' equals zero
[ Upstream commit 1520b4b7ba964f8eec2e7dd14c571d50de3e5191 ]
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 the value of 'lineclock' and
'frameclock' will be zero.
Fix this by checking whether 'pixclock' is zero in kyrofb_check_var().
The following log reveals it:
[ 103.073930] divide error: 0000 [#1] PREEMPT SMP KASAN PTI
[ 103.073942] CPU: 4 PID: 12483 Comm: syz-executor Not tainted 5.14.0-rc2-00478-g2734d6c1b1a0-dirty #118
[ 103.073959] RIP: 0010:kyrofb_set_par+0x316/0xc80
[ 103.074045] Call Trace:
[ 103.074048] ? ___might_sleep+0x1ee/0x2d0
[ 103.074060] ? kyrofb_ioctl+0x330/0x330
[ 103.074069] fb_set_var+0x5bf/0xeb0
[ 103.074078] ? fb_blank+0x1a0/0x1a0
[ 103.074085] ? lock_acquire+0x3bd/0x530
[ 103.074094] ? lock_release+0x810/0x810
[ 103.074103] ? ___might_sleep+0x1ee/0x2d0
[ 103.074114] ? __mutex_lock+0x620/0x1190
[ 103.074126] ? trace_hardirqs_on+0x6a/0x1c0
[ 103.074137] do_fb_ioctl+0x31e/0x700
[ 103.074144] ? fb_getput_cmap+0x280/0x280
[ 103.074152] ? rcu_read_lock_sched_held+0x11/0x80
[ 103.074162] ? rcu_read_lock_sched_held+0x11/0x80
[ 103.074171] ? __sanitizer_cov_trace_switch+0x67/0xf0
[ 103.074181] ? __sanitizer_cov_trace_const_cmp2+0x20/0x80
[ 103.074191] ? do_vfs_ioctl+0x14b/0x16c0
[ 103.074199] ? vfs_fileattr_set+0xb60/0xb60
[ 103.074207] ? rcu_read_lock_sched_held+0x11/0x80
[ 103.074216] ? lock_release+0x483/0x810
[ 103.074224] ? __fget_files+0x217/0x3d0
[ 103.074234] ? __fget_files+0x239/0x3d0
[ 103.074243] ? do_fb_ioctl+0x700/0x700
[ 103.074250] fb_ioctl+0xe6/0x130
Signed-off-by: Zheyu Ma <zheyuma97@xxxxxxxxx>
Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/1627293835-17441-3-git-send-email-zheyuma97@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/video/fbdev/kyro/fbdev.c b/drivers/video/fbdev/kyro/fbdev.c
index d7aa431e6846..74bf26b527b9 100644
--- a/drivers/video/fbdev/kyro/fbdev.c
+++ b/drivers/video/fbdev/kyro/fbdev.c
@@ -399,6 +399,9 @@ static int kyrofb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
struct kyrofb_info *par = info->par;
+ if (!var->pixclock)
+ return -EINVAL;
+
if (var->bits_per_pixel != 16 && var->bits_per_pixel != 32) {
printk(KERN_WARNING "kyrofb: depth not supported: %u\n", var->bits_per_pixel);
return -EINVAL;
