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SubjectRe: [linux-fbdev] Re: Video driver bug (fwd)
From
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The aty128fb patch is good.

> Did anybody test these patches? Currently any user can crash the kernel by
> abusing this bug.
>
> Gr{oetje,eeting}s,
>
> Geert
>
> ---------- Forwarded message ----------
> Date: Sat, 14 Oct 2000 18:21:25 +0200 (CEST)
> From: Geert Uytterhoeven <geert@linux-m68k.org>
> To: Samuel Rydh <samuel@ibrium.se>
> Cc: Linux Frame Buffer Device Development <linux-fbdev@vuser.vu.union.edu>,
> Linux/PPC Development <linuxppc-dev@lists.linuxppc.org>, olh@suse.de
> Subject: Re: [linux-fbdev] Re: Video driver bug
>
> On Sat, 7 Oct 2000, Geert Uytterhoeven wrote:
> > On Sat, 7 Oct 2000, Samuel Rydh wrote:
> > > Certain 2.4 video drivers (aty128, aty, platinum, tdfx, iga)
> > > appear to be buggy. More specifically, the problem is the
> > > following:
> > >
> > > In the set_disp function, info->dispsw is initialized and disp->dispsw
> > > is given the address of info->dispsw:
> > >
> > > static void aty128_set_disp(..)
> > > {
> > > switch(bpp) {
> > > case 8:
> > > info->dispsw = accel ? fbcon_aty128_8 : fbcon_cfb8;
> > > disp->dispsw = &info->dispsw;
> > > break;
> > > ...
> > > }
> > >
> > > The problem is that the info struct is shared by all virtual consoles.
> > > Thus if the video mode is set on a console which is not active, the
> > > active console will be affected too. This typically results in a kernel
> > > panic (the wrong set of console output functions is used).
> >
> > You're right. *_set_disp() may be called for non-active VTs, changing
> > info->dispsw for the active VT.
>
> Here are my fixes for aty128fb, atyfb, platinumfb, and tdfxfb.
>
> Igafb is not affected since it sets disp during initialization only.
>
> Can someone please test these patches so I can send them to Linus? I'm unable
> to test any of them (besides a simple compile test). Thanks!
>
> --- linux-dispsw-fix-2.4.0-test10-pre2/drivers/video/atyfb.c Sun Sep 17 20:04:17 2000
> +++ geert-dispsw-fix-2.4.0-test10-pre2/drivers/video/atyfb.c Sat Oct 14 18:17:40 2000
> @@ -466,8 +466,8 @@
> static int encode_fix(struct fb_fix_screeninfo *fix,
> const struct atyfb_par *par,
> const struct fb_info_aty *info);
> -static void atyfb_set_disp(struct display *disp, struct fb_info_aty *info,
> - int bpp, int accel);
> +static void atyfb_set_dispsw(struct display *disp, struct fb_info_aty *info,
> + int bpp, int accel);
> static int atyfb_getcolreg(u_int regno, u_int *red, u_int *green, u_int *blue,
> u_int *transp, struct fb_info *fb);
> static int atyfb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
> @@ -2826,8 +2826,8 @@
> }
>
>
> -static void atyfb_set_disp(struct display *disp, struct fb_info_aty *info,
> - int bpp, int accel)
> +static void atyfb_set_dispsw(struct display *disp, struct fb_info_aty *info,
> + int bpp, int accel)
> {
> switch (bpp) {
> #ifdef FBCON_HAS_CFB8
> @@ -2898,6 +2898,7 @@
> oldbpp = display->var.bits_per_pixel;
> oldaccel = display->var.accel_flags;
> display->var = *var;
> + accel = var->accel_flags & FB_ACCELF_TEXT;
> if (oldxres != var->xres || oldyres != var->yres ||
> oldvxres != var->xres_virtual || oldvyres != var->yres_virtual ||
> oldbpp != var->bits_per_pixel || oldaccel != var->accel_flags) {
> @@ -2913,8 +2914,6 @@
> display->line_length = fix.line_length;
> display->can_soft_blank = 1;
> display->inverse = 0;
> - accel = var->accel_flags & FB_ACCELF_TEXT;
> - atyfb_set_disp(display, info, par.crtc.bpp, accel);
> if (accel)
> display->scrollmode = (info->bus_type == PCI) ? SCROLL_YNOMOVE : 0;
> else
> @@ -2923,8 +2922,10 @@
> (*info->fb_info.changevar)(con);
> }
> if (!info->fb_info.display_fg ||
> - info->fb_info.display_fg->vc_num == con)
> + info->fb_info.display_fg->vc_num == con) {
> atyfb_set_par(&par, info);
> + atyfb_set_dispsw(display, info, par.crtc.bpp, accel);
> + }
> if (oldbpp != var->bits_per_pixel) {
> if ((err = fb_alloc_cmap(&display->cmap, 0, 0)))
> return err;
> @@ -4241,8 +4242,8 @@
>
> atyfb_decode_var(&fb_display[con].var, &par, info);
> atyfb_set_par(&par, info);
> - atyfb_set_disp(&fb_display[con], info, par.crtc.bpp,
> - par.accel_flags & FB_ACCELF_TEXT);
> + atyfb_set_dispsw(&fb_display[con], info, par.crtc.bpp,
> + par.accel_flags & FB_ACCELF_TEXT);
>
> /* Install new colormap */
> do_install_cmap(con, fb);
> --- linux-dispsw-fix-2.4.0-test10-pre2/drivers/video/tdfxfb.c Fri Jul 28 21:19:20 2000
> +++ geert-dispsw-fix-2.4.0-test10-pre2/drivers/video/tdfxfb.c Sat Oct 14 17:29:21 2000
> @@ -327,7 +327,6 @@
> struct tdfxfb_par default_par;
> struct tdfxfb_par current_par;
> struct display disp;
> - struct display_switch dispsw;
> #if defined(FBCON_HAS_CFB16) || defined(FBCON_HAS_CFB24) || defined(FBCON_HAS_CFB32)
> union {
> #ifdef FBCON_HAS_CFB16
> @@ -412,10 +411,10 @@
> static int tdfxfb_encode_fix(struct fb_fix_screeninfo* fix,
> const struct tdfxfb_par* par,
> const struct fb_info_tdfx* info);
> -static void tdfxfb_set_disp(struct display* disp,
> - struct fb_info_tdfx* info,
> - int bpp,
> - int accel);
> +static void tdfxfb_set_dispsw(struct display* disp,
> + struct fb_info_tdfx* info,
> + int bpp,
> + int accel);
> static int tdfxfb_getcolreg(u_int regno,
> u_int* red,
> u_int* green,
> @@ -1640,48 +1639,43 @@
> return 0;
> }
>
> -static void tdfxfb_set_disp(struct display *disp,
> - struct fb_info_tdfx *info,
> - int bpp,
> - int accel) {
> +static void tdfxfb_set_dispsw(struct display *disp,
> + struct fb_info_tdfx *info,
> + int bpp,
> + int accel) {
>
> if (disp->dispsw && disp->conp)
> fb_con.con_cursor(disp->conp, CM_ERASE);
> switch(bpp) {
> #ifdef FBCON_HAS_CFB8
> case 8:
> - info->dispsw = noaccel ? fbcon_cfb8 : fbcon_banshee8;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = noaccel ? &fbcon_cfb8 : &fbcon_banshee8;
> if (nohwcursor) fbcon_banshee8.cursor = NULL;
> break;
> #endif
> #ifdef FBCON_HAS_CFB16
> case 16:
> - info->dispsw = noaccel ? fbcon_cfb16 : fbcon_banshee16;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = noaccel ? &fbcon_cfb16 : &fbcon_banshee16;
> disp->dispsw_data = info->fbcon_cmap.cfb16;
> if (nohwcursor) fbcon_banshee16.cursor = NULL;
> break;
> #endif
> #ifdef FBCON_HAS_CFB24
> case 24:
> - info->dispsw = noaccel ? fbcon_cfb24 : fbcon_banshee24;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = noaccel ? &fbcon_cfb24 : &fbcon_banshee24;
> disp->dispsw_data = info->fbcon_cmap.cfb24;
> if (nohwcursor) fbcon_banshee24.cursor = NULL;
> break;
> #endif
> #ifdef FBCON_HAS_CFB32
> case 32:
> - info->dispsw = noaccel ? fbcon_cfb32 : fbcon_banshee32;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = noaccel ? &fbcon_cfb32 : &fbcon_banshee32;
> disp->dispsw_data = info->fbcon_cmap.cfb32;
> if (nohwcursor) fbcon_banshee32.cursor = NULL;
> break;
> #endif
> default:
> - info->dispsw = fbcon_dummy;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = &fbcon_dummy;
> }
>
> }
> @@ -1735,7 +1729,7 @@
> display->can_soft_blank = 1;
> display->inverse = inverse;
> accel = var->accel_flags & FB_ACCELF_TEXT;
> - tdfxfb_set_disp(display, info, par.bpp, accel);
> + tdfxfb_set_dispsw(display, info, par.bpp, accel);
>
> if(nopan) display->scrollmode = SCROLL_YREDRAW;
>
> @@ -2083,10 +2077,10 @@
>
> info->cursor.redraw=1;
>
> - tdfxfb_set_disp(&fb_display[con],
> - info,
> - par.bpp,
> - par.accel_flags & FB_ACCELF_TEXT);
> + tdfxfb_set_dispsw(&fb_display[con],
> + info,
> + par.bpp,
> + par.accel_flags & FB_ACCELF_TEXT);
>
> tdfxfb_install_cmap(&fb_display[con], fb);
> tdfxfb_updatevar(con, fb);
> --- linux-dispsw-fix-2.4.0-test10-pre2/drivers/video/aty128fb.c Sun Sep 17 20:04:17 2000
> +++ geert-dispsw-fix-2.4.0-test10-pre2/drivers/video/aty128fb.c Sat Oct 14 17:32:10 2000
> @@ -283,7 +283,6 @@
> const struct aty128_meminfo *mem; /* onboard mem info */
> struct aty128fb_par default_par, current_par;
> struct display disp;
> - struct display_switch dispsw; /* for cursor and font */
> struct { u8 red, green, blue, pad; } palette[256];
> union {
> #ifdef FBCON_HAS_CFB16
> @@ -347,7 +346,7 @@
> static void aty128_encode_fix(struct fb_fix_screeninfo *fix,
> struct aty128fb_par *par,
> const struct fb_info_aty128 *info);
> -static void aty128_set_disp(struct display *disp,
> +static void aty128_set_dispsw(struct display *disp,
> struct fb_info_aty128 *info, int bpp, int accel);
> static int aty128_getcolreg(u_int regno, u_int *red, u_int *green, u_int *blue,
> u_int *transp, struct fb_info *info);
> @@ -1392,7 +1391,7 @@
> display->inverse = 0;
>
> accel = var->accel_flags & FB_ACCELF_TEXT;
> - aty128_set_disp(display, info, par.crtc.bpp, accel);
> + aty128_set_dispsw(display, info, par.crtc.bpp, accel);
>
> if (accel)
> display->scrollmode = SCROLL_YNOMOVE;
> @@ -1417,35 +1416,31 @@
>
>
> static void
> -aty128_set_disp(struct display *disp,
> +aty128_set_dispsw(struct display *disp,
> struct fb_info_aty128 *info, int bpp, int accel)
> {
> switch (bpp) {
> #ifdef FBCON_HAS_CFB8
> case 8:
> - info->dispsw = accel ? fbcon_aty128_8 : fbcon_cfb8;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = accel ? &fbcon_aty128_8 : &fbcon_cfb8;
> break;
> #endif
> #ifdef FBCON_HAS_CFB16
> case 15:
> case 16:
> - info->dispsw = accel ? fbcon_aty128_16 : fbcon_cfb16;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = accel ? &fbcon_aty128_16 : &fbcon_cfb16;
> disp->dispsw_data = info->fbcon_cmap.cfb16;
> break;
> #endif
> #ifdef FBCON_HAS_CFB24
> case 24:
> - info->dispsw = accel ? fbcon_aty128_24 : fbcon_cfb24;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = accel ? &fbcon_aty128_24 : &fbcon_cfb24;
> disp->dispsw_data = info->fbcon_cmap.cfb24;
> break;
> #endif
> #ifdef FBCON_HAS_CFB32
> case 32:
> - info->dispsw = accel ? fbcon_aty128_32 : fbcon_cfb32;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = accel ? &fbcon_aty128_32 : &fbcon_cfb32;
> disp->dispsw_data = info->fbcon_cmap.cfb32;
> break;
> #endif
> @@ -2135,7 +2130,7 @@
> aty128_decode_var(&fb_display[con].var, &par, info);
> aty128_set_par(&par, info);
>
> - aty128_set_disp(&fb_display[con], info, par.crtc.bpp,
> + aty128_set_dispsw(&fb_display[con], info, par.crtc.bpp,
> par.accel_flags & FB_ACCELF_TEXT);
>
> do_install_cmap(con, fb);
> --- linux-dispsw-fix-2.4.0-test10-pre2/drivers/video/platinumfb.c Sat Aug 5 14:20:03 2000
> +++ geert-dispsw-fix-2.4.0-test10-pre2/drivers/video/platinumfb.c Sat Oct 14 17:30:22 2000
> @@ -65,7 +65,6 @@
> struct fb_info_platinum {
> struct fb_info fb_info;
> struct display disp;
> - struct display_switch dispsw;
> struct fb_par_platinum default_par;
> struct fb_par_platinum current_par;
>
> @@ -140,8 +139,9 @@
> static int platinum_encode_fix(struct fb_fix_screeninfo *fix,
> const struct fb_par_platinum *par,
> const struct fb_info_platinum *info);
> -static void platinum_set_disp(struct display *disp, struct fb_info_platinum *info,
> - int cmode, int accel);
> +static void platinum_set_dispsw(struct display *disp,
> + struct fb_info_platinum *info, int cmode,
> + int accel);
> static int platinum_getcolreg(u_int regno, u_int *red, u_int *green, u_int *blue,
> u_int *transp, struct fb_info *fb);
> static int platinum_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
> @@ -193,27 +193,25 @@
> return 0;
> }
>
> -static void platinum_set_disp(struct display *disp, struct fb_info_platinum *info,
> - int cmode, int accel)
> +static void platinum_set_dispsw(struct display *disp,
> + struct fb_info_platinum *info, int cmode,
> + int accel)
> {
> switch(cmode) {
> #ifdef FBCON_HAS_CFB8
> case CMODE_8:
> - info->dispsw = fbcon_cfb8;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = &fbcon_cfb8;
> break;
> #endif
> #ifdef FBCON_HAS_CFB16
> case CMODE_16:
> - info->dispsw = fbcon_cfb16;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = &fbcon_cfb16;
> disp->dispsw_data = info->fbcon_cmap.cfb16;
> break;
> #endif
> #ifdef FBCON_HAS_CFB32
> case CMODE_32:
> - info->dispsw = fbcon_cfb32;
> - disp->dispsw = &info->dispsw;
> + disp->dispsw = &fbcon_cfb32;
> disp->dispsw_data = info->fbcon_cmap.cfb32;
> break;
> #endif
> @@ -271,7 +269,7 @@
> display->line_length = fix.line_length;
> display->can_soft_blank = 1;
> display->inverse = 0;
> - platinum_set_disp(display, info, par.cmode, 0);
> + platinum_set_dispsw(display, info, par.cmode, 0);
> display->scrollmode = SCROLL_YREDRAW;
> if (info->fb_info.changevar)
> (*info->fb_info.changevar)(con);
> @@ -341,7 +339,7 @@
>
> platinum_var_to_par(&fb_display[con].var, &par, info);
> platinum_set_par(&par, info);
> - platinum_set_disp(&fb_display[con], info, par.cmode, 0);
> + platinum_set_dispsw(&fb_display[con], info, par.cmode, 0);
> do_install_cmap(con, fb);
>
> return 1;
>
> Gr{oetje,eeting}s,
>
> Geert

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