[PATCH 3/3] console: Expand dummy functions for CFI
From: Kees Cook
Date: Mon Feb 26 2018 - 19:04:38 EST
This expands the no-op dummy functions into full prototypes to avoid
indirect call mismatches when running under Control Flow Integrity
checking, like with Clang's -fsanitize=cfi.
Co-Developed-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
drivers/usb/misc/sisusbvga/sisusb_con.c | 67 +++++++++++++++++++++++++-------
drivers/video/console/dummycon.c | 69 +++++++++++++++++++++++++--------
drivers/video/console/newport_con.c | 10 ++---
drivers/video/console/vgacon.c | 20 +++++-----
drivers/video/fbdev/core/fbcon.c | 3 +-
5 files changed, 121 insertions(+), 48 deletions(-)
diff --git a/drivers/usb/misc/sisusbvga/sisusb_con.c b/drivers/usb/misc/sisusbvga/sisusb_con.c
index 998df891bdde..a0d6e0af957c 100644
--- a/drivers/usb/misc/sisusbvga/sisusb_con.c
+++ b/drivers/usb/misc/sisusbvga/sisusb_con.c
@@ -1217,7 +1217,7 @@ sisusbcon_do_font_op(struct sisusb_usb_data *sisusb, int set, int slot,
/* Interface routine */
static int
sisusbcon_font_set(struct vc_data *c, struct console_font *font,
- unsigned flags)
+ unsigned int flags)
{
struct sisusb_usb_data *sisusb;
unsigned charcount = font->charcount;
@@ -1338,28 +1338,65 @@ static void sisusbdummycon_init(struct vc_data *vc, int init)
vc_resize(vc, 80, 25);
}
-static int sisusbdummycon_dummy(void)
+static void sisusbdummycon_deinit(struct vc_data *vc) { }
+static void sisusbdummycon_clear(struct vc_data *vc, int sy, int sx,
+ int height, int width) { }
+static void sisusbdummycon_putc(struct vc_data *vc, int c, int ypos,
+ int xpos) { }
+static void sisusbdummycon_putcs(struct vc_data *vc, const unsigned short *s,
+ int count, int ypos, int xpos) { }
+static void sisusbdummycon_cursor(struct vc_data *vc, int mode) { }
+
+static bool sisusbdummycon_scroll(struct vc_data *vc, unsigned int top,
+ unsigned int bottom, enum con_scroll dir,
+ unsigned int lines)
{
- return 0;
+ return false;
}
-#define SISUSBCONDUMMY (void *)sisusbdummycon_dummy
+static int sisusbdummycon_switch(struct vc_data *vc)
+{
+ return 0;
+}
+
+static int sisusbdummycon_blank(struct vc_data *vc, int blank, int mode_switch)
+{
+ return 0;
+}
+
+static int sisusbdummycon_font_set(struct vc_data *vc,
+ struct console_font *font,
+ unsigned int flags)
+{
+ return 0;
+}
+
+static int sisusbdummycon_font_default(struct vc_data *vc,
+ struct console_font *font, char *name)
+{
+ return 0;
+}
+
+static int sisusbdummycon_font_copy(struct vc_data *vc, int con)
+{
+ return 0;
+}
static const struct consw sisusb_dummy_con = {
.owner = THIS_MODULE,
.con_startup = sisusbdummycon_startup,
.con_init = sisusbdummycon_init,
- .con_deinit = SISUSBCONDUMMY,
- .con_clear = SISUSBCONDUMMY,
- .con_putc = SISUSBCONDUMMY,
- .con_putcs = SISUSBCONDUMMY,
- .con_cursor = SISUSBCONDUMMY,
- .con_scroll = SISUSBCONDUMMY,
- .con_switch = SISUSBCONDUMMY,
- .con_blank = SISUSBCONDUMMY,
- .con_font_set = SISUSBCONDUMMY,
- .con_font_default = SISUSBCONDUMMY,
- .con_font_copy = SISUSBCONDUMMY,
+ .con_deinit = sisusbdummycon_deinit,
+ .con_clear = sisusbdummycon_clear,
+ .con_putc = sisusbdummycon_putc,
+ .con_putcs = sisusbdummycon_putcs,
+ .con_cursor = sisusbdummycon_cursor,
+ .con_scroll = sisusbdummycon_scroll,
+ .con_switch = sisusbdummycon_switch,
+ .con_blank = sisusbdummycon_blank,
+ .con_font_set = sisusbdummycon_font_set,
+ .con_font_default = sisusbdummycon_font_default,
+ .con_font_copy = sisusbdummycon_font_copy,
};
int
diff --git a/drivers/video/console/dummycon.c b/drivers/video/console/dummycon.c
index b90ef96e43d6..f2eafe2ed980 100644
--- a/drivers/video/console/dummycon.c
+++ b/drivers/video/console/dummycon.c
@@ -41,12 +41,47 @@ static void dummycon_init(struct vc_data *vc, int init)
vc_resize(vc, DUMMY_COLUMNS, DUMMY_ROWS);
}
-static int dummycon_dummy(void)
+static void dummycon_deinit(struct vc_data *vc) { }
+static void dummycon_clear(struct vc_data *vc, int sy, int sx, int height,
+ int width) { }
+static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
+static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
+ int count, int ypos, int xpos) { }
+static void dummycon_cursor(struct vc_data *vc, int mode) { }
+
+static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
+ unsigned int bottom, enum con_scroll dir,
+ unsigned int lines)
+{
+ return false;
+}
+
+static int dummycon_switch(struct vc_data *vc)
{
- return 0;
+ return 0;
}
-#define DUMMY (void *)dummycon_dummy
+static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
+{
+ return 0;
+}
+
+static int dummycon_font_set(struct vc_data *vc, struct console_font *font,
+ unsigned int flags)
+{
+ return 0;
+}
+
+static int dummycon_font_default(struct vc_data *vc,
+ struct console_font *font, char *name)
+{
+ return 0;
+}
+
+static int dummycon_font_copy(struct vc_data *vc, int con)
+{
+ return 0;
+}
/*
* The console `switch' structure for the dummy console
@@ -55,19 +90,19 @@ static int dummycon_dummy(void)
*/
const struct consw dummy_con = {
- .owner = THIS_MODULE,
- .con_startup = dummycon_startup,
- .con_init = dummycon_init,
- .con_deinit = DUMMY,
- .con_clear = DUMMY,
- .con_putc = DUMMY,
- .con_putcs = DUMMY,
- .con_cursor = DUMMY,
- .con_scroll = DUMMY,
- .con_switch = DUMMY,
- .con_blank = DUMMY,
- .con_font_set = DUMMY,
- .con_font_default = DUMMY,
- .con_font_copy = DUMMY,
+ .owner = THIS_MODULE,
+ .con_startup = dummycon_startup,
+ .con_init = dummycon_init,
+ .con_deinit = dummycon_deinit,
+ .con_clear = dummycon_clear,
+ .con_putc = dummycon_putc,
+ .con_putcs = dummycon_putcs,
+ .con_cursor = dummycon_cursor,
+ .con_scroll = dummycon_scroll,
+ .con_switch = dummycon_switch,
+ .con_blank = dummycon_blank,
+ .con_font_set = dummycon_font_set,
+ .con_font_default = dummycon_font_default,
+ .con_font_copy = dummycon_font_copy,
};
EXPORT_SYMBOL_GPL(dummy_con);
diff --git a/drivers/video/console/newport_con.c b/drivers/video/console/newport_con.c
index 42d02a206059..6897bd0fc00e 100644
--- a/drivers/video/console/newport_con.c
+++ b/drivers/video/console/newport_con.c
@@ -673,14 +673,14 @@ static bool newport_scroll(struct vc_data *vc, unsigned int t, unsigned int b,
return true;
}
-static int newport_dummy(struct vc_data *c)
+static int newport_set_origin(struct vc_data *vc)
{
return 0;
}
-#define DUMMY (void *) newport_dummy
+static void newport_save_screen(struct vc_data *vc) { }
-const struct consw newport_con = {
+static const struct consw newport_con = {
.owner = THIS_MODULE,
.con_startup = newport_startup,
.con_init = newport_init,
@@ -694,8 +694,8 @@ const struct consw newport_con = {
.con_blank = newport_blank,
.con_font_set = newport_font_set,
.con_font_default = newport_font_default,
- .con_set_origin = DUMMY,
- .con_save_screen = DUMMY
+ .con_set_origin = newport_set_origin,
+ .con_save_screen = newport_save_screen
};
static int newport_probe(struct gio_device *dev,
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index a17ba1465815..f09e17b60e45 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -1272,7 +1272,8 @@ static int vgacon_adjust_height(struct vc_data *vc, unsigned fontheight)
return 0;
}
-static int vgacon_font_set(struct vc_data *c, struct console_font *font, unsigned flags)
+static int vgacon_font_set(struct vc_data *c, struct console_font *font,
+ unsigned int flags)
{
unsigned charcount = font->charcount;
int rc;
@@ -1407,21 +1408,20 @@ static bool vgacon_scroll(struct vc_data *c, unsigned int t, unsigned int b,
* The console `switch' structure for the VGA based console
*/
-static int vgacon_dummy(struct vc_data *c)
-{
- return 0;
-}
-
-#define DUMMY (void *) vgacon_dummy
+static void vgacon_clear(struct vc_data *vc, int sy, int sx, int height,
+ int width) { }
+static void vgacon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
+static void vgacon_putcs(struct vc_data *vc, const unsigned short *s,
+ int count, int ypos, int xpos) { }
const struct consw vga_con = {
.owner = THIS_MODULE,
.con_startup = vgacon_startup,
.con_init = vgacon_init,
.con_deinit = vgacon_deinit,
- .con_clear = DUMMY,
- .con_putc = DUMMY,
- .con_putcs = DUMMY,
+ .con_clear = vgacon_clear,
+ .con_putc = vgacon_putc,
+ .con_putcs = vgacon_putcs,
.con_cursor = vgacon_cursor,
.con_scroll = vgacon_scroll,
.con_switch = vgacon_switch,
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 5baf7bc054e1..3e330e0f56ed 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -2595,7 +2595,8 @@ static int fbcon_copy_font(struct vc_data *vc, int con)
* is ever implemented.
*/
-static int fbcon_set_font(struct vc_data *vc, struct console_font *font, unsigned flags)
+static int fbcon_set_font(struct vc_data *vc, struct console_font *font,
+ unsigned int flags)
{
struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
unsigned charcount = font->charcount;
--
2.7.4