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From: Yizhuo Zhai <yzhai003@ucr.edu>
To: unlisted-recipients:; (no To-header on input)
Cc: Yizhuo Zhai <yzhai003@ucr.edu>, Helge Deller <deller@gmx.de>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Matthew Wilcox <willy@infradead.org>,
	Sam Ravnborg <sam@ravnborg.org>, Xin Tan <tanxin.ctf@gmail.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Zheyu Ma <zheyuma97@gmail.com>,
	Guenter Roeck <linux@roeck-us.net>,
	Alex Deucher <alexander.deucher@amd.com>,
	Zhen Lei <thunder.leizhen@huawei.com>,
	Xiyu Yang <xiyuyang19@fudan.edu.cn>,
	linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v3] fbdev: fbmem: Fix the implicit type casting
Date: Tue,  1 Feb 2022 02:56:08 -0800	[thread overview]
Message-ID: <20220201105610.2975873-2-yzhai003@ucr.edu> (raw)
In-Reply-To: <20220201105610.2975873-1-yzhai003@ucr.edu>

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@ucr.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


WARNING: multiple messages have this Message-ID (diff)
From: Yizhuo Zhai <yzhai003@ucr.edu>
Cc: Xin Tan <tanxin.ctf@gmail.com>,
	Xiyu Yang <xiyuyang19@fudan.edu.cn>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	Helge Deller <deller@gmx.de>, Zheyu Ma <zheyuma97@gmail.com>,
	linux-fbdev@vger.kernel.org, Matthew Wilcox <willy@infradead.org>,
	linux-kernel@vger.kernel.org, Yizhuo Zhai <yzhai003@ucr.edu>,
	dri-devel@lists.freedesktop.org,
	Zhen Lei <thunder.leizhen@huawei.com>,
	Alex Deucher <alexander.deucher@amd.com>,
	Sam Ravnborg <sam@ravnborg.org>,
	Guenter Roeck <linux@roeck-us.net>
Subject: [PATCH v3] fbdev: fbmem: Fix the implicit type casting
Date: Tue,  1 Feb 2022 02:56:08 -0800	[thread overview]
Message-ID: <20220201105610.2975873-2-yzhai003@ucr.edu> (raw)
In-Reply-To: <20220201105610.2975873-1-yzhai003@ucr.edu>

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@ucr.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


  reply	other threads:[~2022-02-01 10:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-01 10:42 drivers/video/fbdev/core/fbmem.c:1165:21: error: 'blank' undeclared; did you mean 'fb_blank'? kernel test robot
2022-02-01 10:42 ` kernel test robot
2022-02-01 10:56 ` [PATCH v3] fbdev: fbmem: Fix the implicit type casting Yizhuo Zhai
2022-02-01 10:56   ` Yizhuo Zhai
2022-02-01 10:56   ` Yizhuo Zhai [this message]
2022-02-01 10:56     ` Yizhuo Zhai

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