From fcee2ee6144035f9d62b6ce985672fbe7e8b9c46 Mon Sep 17 00:00:00 2001
From: Zheyu Ma <zheyuma97@gmail.com>
Date: Mon, 26 Jul 2021 10:03:55 +0000
Subject: video: fbdev: riva: Error out if 'pixclock' equals zero
Git-commit: f92763cb0feba247e0939ed137b495601fd072a5
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
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:
[ 33.396850] divide error: 0000 [#1] PREEMPT SMP KASAN PTI
[ 33.396864] CPU: 5 PID: 11754 Comm: i740 Not tainted 5.14.0-rc2-00513-gac532c9bbcfb-dirty #222
[ 33.396883] RIP: 0010:riva_load_video_mode+0x417/0xf70
[ 33.396969] Call Trace:
[ 33.396973] ? debug_smp_processor_id+0x1c/0x20
[ 33.396984] ? tick_nohz_tick_stopped+0x1a/0x90
[ 33.396996] ? rivafb_copyarea+0x3c0/0x3c0
[ 33.397003] ? wake_up_klogd.part.0+0x99/0xd0
[ 33.397014] ? vprintk_emit+0x110/0x4b0
[ 33.397024] ? vprintk_default+0x26/0x30
[ 33.397033] ? vprintk+0x9c/0x1f0
[ 33.397041] ? printk+0xba/0xed
[ 33.397054] ? record_print_text.cold+0x16/0x16
[ 33.397063] ? __kasan_check_read+0x11/0x20
[ 33.397074] ? profile_tick+0xc0/0x100
[ 33.397084] ? __sanitizer_cov_trace_const_cmp4+0x24/0x80
[ 33.397094] ? riva_set_rop_solid+0x2a0/0x2a0
[ 33.397102] rivafb_set_par+0xbe/0x610
[ 33.397111] ? riva_set_rop_solid+0x2a0/0x2a0
[ 33.397119] fb_set_var+0x5bf/0xeb0
[ 33.397127] ? fb_blank+0x1a0/0x1a0
[ 33.397134] ? lock_acquire+0x1ef/0x530
[ 33.397143] ? lock_release+0x810/0x810
[ 33.397151] ? lock_is_held_type+0x100/0x140
[ 33.397159] ? ___might_sleep+0x1ee/0x2d0
[ 33.397170] ? __mutex_lock+0x620/0x1190
[ 33.397180] ? trace_hardirqs_on+0x6a/0x1c0
[ 33.397190] 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/1627293835-17441-4-git-send-email-zheyuma97@gmail.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/video/fbdev/riva/fbdev.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/video/fbdev/riva/fbdev.c b/drivers/video/fbdev/riva/fbdev.c
index 55554b0433cb..84d5e23ad7d3 100644
--- a/drivers/video/fbdev/riva/fbdev.c
+++ b/drivers/video/fbdev/riva/fbdev.c
@@ -1084,6 +1084,9 @@ static int rivafb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
int mode_valid = 0;
NVTRACE_ENTER();
+ if (!var->pixclock)
+ return -EINVAL;
+
switch (var->bits_per_pixel) {
case 1 ... 8:
var->red.offset = var->green.offset = var->blue.offset = 0;
--
2.38.1