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console: Expand dummy functions for CFI
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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@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Kees Cook authored and Greg Kroah-Hartman committed Feb 27, 2018
1 parent 209f668 commit c396a5b
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Showing 5 changed files with 121 additions and 48 deletions.
67 changes: 52 additions & 15 deletions drivers/usb/misc/sisusbvga/sisusb_con.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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
Expand Down
69 changes: 52 additions & 17 deletions drivers/video/console/dummycon.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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);
10 changes: 5 additions & 5 deletions drivers/video/console/newport_con.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand All @@ -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,
Expand Down
20 changes: 10 additions & 10 deletions drivers/video/console/vgacon.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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,
Expand Down
3 changes: 2 additions & 1 deletion drivers/video/fbdev/core/fbcon.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down

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