From aba16e2c8931e5b6bc3cad185b436a38dc4726c1 Mon Sep 17 00:00:00 2001
From: Zheyu Ma <zheyuma97@gmail.com>
Date: Mon, 26 Jul 2021 10:03:55 +0000
Subject: [PATCH] video: fbdev: riva: Error out if 'pixclock' equals zero
Git-commit: f92763cb0feba247e0939ed137b495601fd072a5
Patch-mainline: v5.15-rc1
References: stable-5.14.6
[ Upstream commit f92763cb0feba247e0939ed137b495601fd072a5 ]
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
Signed-off-by: Sasha Levin <sashal@kernel.org>
Acked-by: Takashi Iwai <tiwai@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;
--
2.26.2