From e400b6ec4ede4dc0aa8e5640425df5b29796fe0e Mon Sep 17 00:00:00 2001 From: "Antonino A. Daplas" Date: Tue, 16 Oct 2007 01:29:35 -0700 Subject: [PATCH] vt/vgacon: Check if screen resize request comes from userspace Various console drivers are able to resize the screen via the con_resize() hook. This hook is also visible in userspace via the TIOCWINSZ, VT_RESIZE and VT_RESIZEX ioctl's. One particular utility, SVGATextMode, expects that con_resize() of the VGA console will always return success even if the resulting screen is not compatible with the hardware. However, this particular behavior of the VGA console, as reported in Kernel Bugzilla Bug 7513, can cause undefined behavior if the user starts with a console size larger than 80x25. To work around this problem, add an extra parameter to con_resize(). This parameter is ignored by drivers except for vgacon. If this parameter is non-zero, then the resize request came from a VT_RESIZE or VT_RESIZEX ioctl and vgacon will always return success. If this parameter is zero, vgacon will return -EINVAL if the requested size is not compatible with the hardware. The latter is the more correct behavior. With this change, SVGATextMode should still work correctly while in-kernel and stty resize calls can expect correct behavior from vgacon. Signed-off-by: Antonino Daplas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/char/vt.c | 13 +++++++++---- drivers/char/vt_ioctl.c | 15 +++++++++++++-- drivers/usb/misc/sisusbvga/sisusb_con.c | 3 ++- drivers/video/console/fbcon.c | 2 +- drivers/video/console/vgacon.c | 7 ++++--- include/linux/console.h | 3 ++- include/linux/console_struct.h | 1 + 7 files changed, 32 insertions(+), 12 deletions(-) diff --git a/drivers/char/vt.c b/drivers/char/vt.c index edb7002a3216..0d56f8fc105c 100644 --- a/drivers/char/vt.c +++ b/drivers/char/vt.c @@ -750,13 +750,15 @@ int vc_allocate(unsigned int currcons) /* return 0 on success */ return 0; } -static inline int resize_screen(struct vc_data *vc, int width, int height) +static inline int resize_screen(struct vc_data *vc, int width, int height, + int user) { /* Resizes the resolution of the display adapater */ int err = 0; if (vc->vc_mode != KD_GRAPHICS && vc->vc_sw->con_resize) - err = vc->vc_sw->con_resize(vc, width, height); + err = vc->vc_sw->con_resize(vc, width, height, user); + return err; } @@ -772,7 +774,7 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines) unsigned long old_origin, new_origin, new_scr_end, rlth, rrem, err = 0; unsigned int old_cols, old_rows, old_row_size, old_screen_size; unsigned int new_cols, new_rows, new_row_size, new_screen_size; - unsigned int end; + unsigned int end, user; unsigned short *newscreen; WARN_CONSOLE_UNLOCKED(); @@ -780,6 +782,9 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines) if (!vc) return -ENXIO; + user = vc->vc_resize_user; + vc->vc_resize_user = 0; + if (cols > VC_RESIZE_MAXCOL || lines > VC_RESIZE_MAXROW) return -EINVAL; @@ -800,7 +805,7 @@ int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int lines) old_row_size = vc->vc_size_row; old_screen_size = vc->vc_screenbuf_size; - err = resize_screen(vc, new_cols, new_rows); + err = resize_screen(vc, new_cols, new_rows, user); if (err) { kfree(newscreen); return err; diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c index 7a61a2a9aafe..f69a8258095c 100644 --- a/drivers/char/vt_ioctl.c +++ b/drivers/char/vt_ioctl.c @@ -847,14 +847,24 @@ int vt_ioctl(struct tty_struct *tty, struct file * file, case VT_RESIZE: { struct vt_sizes __user *vtsizes = up; + struct vc_data *vc; + ushort ll,cc; if (!perm) return -EPERM; if (get_user(ll, &vtsizes->v_rows) || get_user(cc, &vtsizes->v_cols)) return -EFAULT; - for (i = 0; i < MAX_NR_CONSOLES; i++) - vc_lock_resize(vc_cons[i].d, cc, ll); + + for (i = 0; i < MAX_NR_CONSOLES; i++) { + vc = vc_cons[i].d; + + if (vc) { + vc->vc_resize_user = 1; + vc_lock_resize(vc_cons[i].d, cc, ll); + } + } + return 0; } @@ -900,6 +910,7 @@ int vt_ioctl(struct tty_struct *tty, struct file * file, vc_cons[i].d->vc_scan_lines = vlin; if (clin) vc_cons[i].d->vc_font.height = clin; + vc_cons[i].d->vc_resize_user = 1; vc_resize(vc_cons[i].d, cc, ll); release_console_sem(); } diff --git a/drivers/usb/misc/sisusbvga/sisusb_con.c b/drivers/usb/misc/sisusbvga/sisusb_con.c index 43722e5a49d1..b624320df903 100644 --- a/drivers/usb/misc/sisusbvga/sisusb_con.c +++ b/drivers/usb/misc/sisusbvga/sisusb_con.c @@ -1042,7 +1042,8 @@ sisusbcon_set_origin(struct vc_data *c) /* Interface routine */ static int -sisusbcon_resize(struct vc_data *c, unsigned int newcols, unsigned int newrows) +sisusbcon_resize(struct vc_data *c, unsigned int newcols, unsigned int newrows, + unsigned int user) { struct sisusb_usb_data *sisusb; int fh; diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c index 6d0dcde66eb4..97a0224a0cf0 100644 --- a/drivers/video/console/fbcon.c +++ b/drivers/video/console/fbcon.c @@ -2168,7 +2168,7 @@ static __inline__ void updatescrollmode(struct display *p, } static int fbcon_resize(struct vc_data *vc, unsigned int width, - unsigned int height) + unsigned int height, unsigned int user) { struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]]; struct fbcon_ops *ops = info->fbcon_par; diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c index d18b73aafa0d..e9afb7ebd566 100644 --- a/drivers/video/console/vgacon.c +++ b/drivers/video/console/vgacon.c @@ -1278,13 +1278,14 @@ static int vgacon_font_get(struct vc_data *c, struct console_font *font) #endif static int vgacon_resize(struct vc_data *c, unsigned int width, - unsigned int height) + unsigned int height, unsigned int user) { if (width % 2 || width > ORIG_VIDEO_COLS || height > (ORIG_VIDEO_LINES * vga_default_font_height)/ c->vc_font.height) - /* let svgatextmode tinker with video timings */ - return 0; + /* let svgatextmode tinker with video timings and + return success */ + return (user) ? 0 : -EINVAL; if (CON_IS_VISIBLE(c) && !vga_is_gfx) /* who knows */ vgacon_doresize(c, width, height); diff --git a/include/linux/console.h b/include/linux/console.h index 56a7bcda49cb..0a4542ddb73d 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -45,7 +45,8 @@ struct consw { int (*con_font_get)(struct vc_data *, struct console_font *); int (*con_font_default)(struct vc_data *, struct console_font *, char *); int (*con_font_copy)(struct vc_data *, int); - int (*con_resize)(struct vc_data *, unsigned int, unsigned int); + int (*con_resize)(struct vc_data *, unsigned int, unsigned int, + unsigned int); int (*con_set_palette)(struct vc_data *, unsigned char *); int (*con_scrolldelta)(struct vc_data *, int); int (*con_set_origin)(struct vc_data *); diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h index dc77fed7b285..d71f7c0f931b 100644 --- a/include/linux/console_struct.h +++ b/include/linux/console_struct.h @@ -100,6 +100,7 @@ struct vc_data { unsigned char vc_G1_charset; unsigned char vc_saved_G0; unsigned char vc_saved_G1; + unsigned int vc_resize_user; /* resize request from user */ unsigned int vc_bell_pitch; /* Console bell pitch */ unsigned int vc_bell_duration; /* Console bell duration */ struct vc_data **vc_display_fg; /* [!] Ptr to var holding fg console for this display */