From: Zheyu Ma zheyuma97@gmail.com
[ 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@gmail.com Signed-off-by: Sam Ravnborg sam@ravnborg.org Link: https://patchwork.freedesktop.org/patch/msgid/1627293835-17441-3-git-send-em... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/video/fbdev/kyro/fbdev.c | 3 +++ 1 file changed, 3 insertions(+)
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;