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Message-Id: <20220201105610.2975873-2-yzhai003@ucr.edu>
Date: Tue, 1 Feb 2022 02:56:08 -0800
From: Yizhuo Zhai <yzhai003@....edu>
To: unlisted-recipients:; (no To-header on input)
Cc: Yizhuo Zhai <yzhai003@....edu>, Helge Deller <deller@....de>,
Daniel Vetter <daniel.vetter@...ll.ch>,
Matthew Wilcox <willy@...radead.org>,
Sam Ravnborg <sam@...nborg.org>,
Xin Tan <tanxin.ctf@...il.com>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
Zheyu Ma <zheyuma97@...il.com>,
Guenter Roeck <linux@...ck-us.net>,
Alex Deucher <alexander.deucher@....com>,
Zhen Lei <thunder.leizhen@...wei.com>,
Xiyu Yang <xiyuyang19@...an.edu.cn>,
linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v3] fbdev: fbmem: Fix the implicit type casting
In function do_fb_ioctl(), the "arg" is the type of unsigned long,
and in "case FBIOBLANK:" this argument is casted into an int before
passig to fb_blank(). In fb_blank(), the comparision
if (blank > FB_BLANK_POWERDOWN) would be bypass if the original
"arg" is a large number, which is possible because it comes from
the user input. Fix this by adding the check before the function
call.
Signed-off-by: Yizhuo Zhai <yzhai003@....edu>
---
drivers/video/fbdev/core/fbmem.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 0fa7ede94fa6..991711bfd647 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1162,6 +1162,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd,
case FBIOBLANK:
console_lock();
lock_fb_info(info);
+ if (arg > FB_BLANK_POWERDOWN)
+ arg = FB_BLANK_POWERDOWN;
ret = fb_blank(info, arg);
/* might again call into fb_blank */
fbcon_fb_blanked(info, arg);
--
2.25.1
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