From: Helge Deller deller@gmx.de
commit cad564ca557f8d3bb3b1fa965d9a2b3f6490ec69 upstream.
The user may use the fbcon=vc:<n1>-<n2> option to tell fbcon to take over the given range (n1...n2) of consoles. The value for n1 and n2 needs to be a positive number and up to (MAX_NR_CONSOLES - 1). The given values were not fully checked against those boundaries yet.
To fix the issue, convert first_fb_vc and last_fb_vc to unsigned integers and check them against the upper boundary, and make sure that first_fb_vc is smaller than last_fb_vc.
Cc: stable@vger.kernel.org # v4.19+ Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Helge Deller deller@gmx.de Link: https://patchwork.freedesktop.org/patch/msgid/YpkYRMojilrtZIgM@p100 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/video/fbdev/core/fbcon.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -103,8 +103,8 @@ static int logo_lines; enums. */ static int logo_shown = FBCON_LOGO_CANSHOW; /* console mappings */ -static int first_fb_vc; -static int last_fb_vc = MAX_NR_CONSOLES - 1; +static unsigned int first_fb_vc; +static unsigned int last_fb_vc = MAX_NR_CONSOLES - 1; static int fbcon_is_default = 1; static int fbcon_has_exited; static int primary_device = -1; @@ -456,10 +456,12 @@ static int __init fb_console_setup(char options += 3; if (*options) first_fb_vc = simple_strtoul(options, &options, 10) - 1; - if (first_fb_vc < 0) + if (first_fb_vc >= MAX_NR_CONSOLES) first_fb_vc = 0; if (*options++ == '-') last_fb_vc = simple_strtoul(options, &options, 10) - 1; + if (last_fb_vc < first_fb_vc || last_fb_vc >= MAX_NR_CONSOLES) + last_fb_vc = MAX_NR_CONSOLES - 1; fbcon_is_default = 0; continue; }