| Message ID | 20220202235811.1621017-2-yzhai003@ucr.edu (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | [v6] fbdev: fbmem: Fix the implicit type casting | expand |
On Wed, Feb 02, 2022 at 03:58:09PM -0800, Yizhuo Zhai wrote: > 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> Reviewed-by: Guenter Roeck <linux@roeck-us.net> On a side note, change logs would be useful. Guenter > --- > 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..13083ad8d751 100644 > --- a/drivers/video/fbdev/core/fbmem.c > +++ b/drivers/video/fbdev/core/fbmem.c > @@ -1160,6 +1160,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, > ret = fbcon_set_con2fb_map_ioctl(argp); > break; > case FBIOBLANK: > + if (arg > FB_BLANK_POWERDOWN) > + return -EINVAL; > console_lock(); > lock_fb_info(info); > ret = fb_blank(info, arg); > -- > 2.25.1 >
diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index 0fa7ede94fa6..13083ad8d751 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1160,6 +1160,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, ret = fbcon_set_con2fb_map_ioctl(argp); break; case FBIOBLANK: + if (arg > FB_BLANK_POWERDOWN) + return -EINVAL; console_lock(); lock_fb_info(info); ret = fb_blank(info, arg);
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(+)