linux-stable.git/drivers/video/fbdev/core, branch v4.19.201

tty: vt: always invoke vc->vc_sw->con_resize callback

2021-05-26T09:48:35+00:00

commit ffb324e6f874121f7dce5bdae5e05d02baae7269 upstream.

syzbot is reporting OOB write at vga16fb_imageblit() [1], for
resize_screen() from ioctl(VT_RESIZE) returns 0 without checking whether
requested rows/columns fit the amount of memory reserved for the graphical
screen if current mode is KD_GRAPHICS.

----------
  #include 
  #include 
  #include 
  #include 
  #include 
  #include 

  int main(int argc, char *argv[])
  {
        const int fd = open("/dev/char/4:1", O_RDWR);
        struct vt_sizes vt = { 0x4100, 2 };

        ioctl(fd, KDSETMODE, KD_GRAPHICS);
        ioctl(fd, VT_RESIZE, &vt);
        ioctl(fd, KDSETMODE, KD_TEXT);
        return 0;
  }
----------

Allow framebuffer drivers to return -EINVAL, by moving vc->vc_mode !=
KD_GRAPHICS check from resize_screen() to fbcon_resize().

Link: https://syzkaller.appspot.com/bug?extid=1f29e126cf461c4de3b3 [1]
Reported-by: syzbot 
Suggested-by: Linus Torvalds 
Signed-off-by: Tetsuo Handa 
Tested-by: syzbot 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fbdev: zero-fill colormap in fbcmap.c

2021-05-22T08:59:14+00:00

commit 19ab233989d0f7ab1de19a036e247afa4a0a1e9c upstream.

Use kzalloc() rather than kmalloc() for the dynamically allocated parts
of the colormap in fb_alloc_cmap_gfp, to prevent a leak of random kernel
data to userspace under certain circumstances.

Fixes a KMSAN-found infoleak bug reported by syzbot at:
https://syzkaller.appspot.com/bug?id=741578659feabd108ad9e06696f0c1f2e69c4b6e

Reported-by: syzbot+47fa9c9c648b765305b9@syzkaller.appspotmail.com
Cc: stable 
Reviewed-by: Geert Uytterhoeven 
Signed-off-by: Phillip Potter 
Link: https://lore.kernel.org/r/20210331220719.1499743-1-phil@philpotter.co.uk
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

drivers: video: fbcon: fix NULL dereference in fbcon_cursor()

2021-04-07T10:48:51+00:00

commit 01faae5193d6190b7b3aa93dae43f514e866d652 upstream.

add null-check on function pointer before dereference on ops->cursor

Reported-by: syzbot+b67aaae8d3a927f68d20@syzkaller.appspotmail.com
Cc: stable 
Signed-off-by: Du Cheng 
Link: https://lore.kernel.org/r/20210312081421.452405-1-ducheng2@gmail.com
Signed-off-by: Greg Kroah-Hartman

fbcon: Fix global-out-of-bounds read in fbcon_get_font()

2020-10-14T08:31:21+00:00

commit 5af08640795b2b9a940c9266c0260455377ae262 upstream.

fbcon_get_font() is reading out-of-bounds. A malicious user may resize
`vc->vc_font.height` to a large value, causing fbcon_get_font() to
read out of `fontdata`.

fbcon_get_font() handles both built-in and user-provided fonts.
Fortunately, recently we have added FONT_EXTRA_WORDS support for built-in
fonts, so fix it by adding range checks using FNTSIZE().

This patch depends on patch "fbdev, newport_con: Move FONT_EXTRA_WORDS
macros into linux/font.h", and patch "Fonts: Support FONT_EXTRA_WORDS
macros for built-in fonts".

Cc: stable@vger.kernel.org
Reported-and-tested-by: syzbot+29d4ed7f3bdedf2aa2fd@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=08b8be45afea11888776f897895aef9ad1c3ecfd
Signed-off-by: Peilin Ye 
Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Daniel Vetter 
Link: https://patchwork.freedesktop.org/patch/msgid/b34544687a1a09d6de630659eb7a773f4953238b.1600953813.git.yepeilin.cs@gmail.com
Signed-off-by: Greg Kroah-Hartman

fbdev, newport_con: Move FONT_EXTRA_WORDS macros into linux/font.h

2020-10-14T08:31:21+00:00

commit bb0890b4cd7f8203e3aa99c6d0f062d6acdaad27 upstream.

drivers/video/console/newport_con.c is borrowing FONT_EXTRA_WORDS macros
from drivers/video/fbdev/core/fbcon.h. To keep things simple, move all
definitions into .

Since newport_con now uses four extra words, initialize the fourth word in
newport_set_font() properly.

Cc: stable@vger.kernel.org
Signed-off-by: Peilin Ye 
Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Daniel Vetter 
Link: https://patchwork.freedesktop.org/patch/msgid/7fb8bc9b0abc676ada6b7ac0e0bd443499357267.1600953813.git.yepeilin.cs@gmail.com
Signed-off-by: Greg Kroah-Hartman

fbcon: Fix user font detection test at fbcon_resize().

2020-09-23T10:11:00+00:00

[ Upstream commit ec0972adecb391a8d8650832263a4790f3bfb4df ]

syzbot is reporting OOB read at fbcon_resize() [1], for
commit 39b3cffb8cf31117 ("fbcon: prevent user font height or width change
 from causing potential out-of-bounds access") is by error using
registered_fb[con2fb_map[vc->vc_num]]->fbcon_par->p->userfont (which was
set to non-zero) instead of fb_display[vc->vc_num].userfont (which remains
zero for that display).

We could remove tricky userfont flag [2], for we can determine it by
comparing address of the font data and addresses of built-in font data.
But since that commit is failing to fix the original OOB read [3], this
patch keeps the change minimal in case we decide to revert altogether.

[1] https://syzkaller.appspot.com/bug?id=ebcbbb6576958a496500fee9cf7aa83ea00b5920
[2] https://syzkaller.appspot.com/text?tag=Patch&x=14030853900000
[3] https://syzkaller.appspot.com/bug?id=6fba8c186d97cf1011ab17660e633b1cc4e080c9

Reported-by: syzbot 
Signed-off-by: Tetsuo Handa 
Fixes: 39b3cffb8cf31117 ("fbcon: prevent user font height or width change from causing potential out-of-bounds access")
Cc: George Kennedy 
Link: https://lore.kernel.org/r/f6e3e611-8704-1263-d163-f52c906a4f06@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

fbcon: remove now unusued 'softback_lines' cursor() argument

2020-09-17T11:45:30+00:00

commit 06a0df4d1b8b13b551668e47b11fd7629033b7df upstream.

Since the softscroll code got removed, this argument is always zero and
makes no sense any more.

Tested-by: Yuan Ming 
Tested-by: Willy Tarreau 
Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fbcon: remove soft scrollback code

2020-09-17T11:45:30+00:00

commit 50145474f6ef4a9c19205b173da6264a644c7489 upstream.

This (and the VGA soft scrollback) turns out to have various nasty small
special cases that nobody really is willing to fight.  The soft
scrollback code was really useful a few decades ago when you typically
used the console interactively as the main way to interact with the
machine, but that just isn't the case any more.

So it's not worth dragging along.

Tested-by: Yuan Ming 
Tested-by: Willy Tarreau 
Acked-by: Bartlomiej Zolnierkiewicz 
Acked-by: Daniel Vetter 
Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fbcon: prevent user font height or width change from causing potential out-of-bounds access

2020-09-03T09:24:27+00:00

commit 39b3cffb8cf3111738ea993e2757ab382253d86a upstream.

Add a check to fbcon_resize() to ensure that a possible change to user font
height or user font width will not allow a font data out-of-bounds access.
NOTE: must use original charcount in calculation as font charcount can
change and cannot be used to determine the font data allocated size.

Signed-off-by: George Kennedy 
Cc: stable 
Reported-by: syzbot+38a3699c7eaf165b97a6@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/1596213192-6635-1-git-send-email-george.kennedy@oracle.com
Signed-off-by: Greg Kroah-Hartman

fbdev: Detect integer underflow at "struct fbcon_ops"->clear_margins.

2020-07-29T08:16:56+00:00

commit 033724d6864245a11f8e04c066002e6ad22b3fd0 upstream.

syzbot is reporting general protection fault in bitfill_aligned() [1]
caused by integer underflow in bit_clear_margins(). The cause of this
problem is when and how do_vc_resize() updates vc->vc_{cols,rows}.

If vc_do_resize() fails (e.g. kzalloc() fails) when var.xres or var.yres
is going to shrink, vc->vc_{cols,rows} will not be updated. This allows
bit_clear_margins() to see info->var.xres < (vc->vc_cols * cw) or
info->var.yres < (vc->vc_rows * ch). Unexpectedly large rw or bh will
try to overrun the __iomem region and causes general protection fault.

Also, vc_resize(vc, 0, 0) does not set vc->vc_{cols,rows} = 0 due to

  new_cols = (cols ? cols : vc->vc_cols);
  new_rows = (lines ? lines : vc->vc_rows);

exception. Since cols and lines are calculated as

  cols = FBCON_SWAP(ops->rotate, info->var.xres, info->var.yres);
  rows = FBCON_SWAP(ops->rotate, info->var.yres, info->var.xres);
  cols /= vc->vc_font.width;
  rows /= vc->vc_font.height;
  vc_resize(vc, cols, rows);

in fbcon_modechanged(), var.xres < vc->vc_font.width makes cols = 0
and var.yres < vc->vc_font.height makes rows = 0. This means that

  const int fd = open("/dev/fb0", O_ACCMODE);
  struct fb_var_screeninfo var = { };
  ioctl(fd, FBIOGET_VSCREENINFO, &var);
  var.xres = var.yres = 1;
  ioctl(fd, FBIOPUT_VSCREENINFO, &var);

easily reproduces integer underflow bug explained above.

Of course, callers of vc_resize() are not handling vc_do_resize() failure
is bad. But we can't avoid vc_resize(vc, 0, 0) which returns 0. Therefore,
as a band-aid workaround, this patch checks integer underflow in
"struct fbcon_ops"->clear_margins call, assuming that
vc->vc_cols * vc->vc_font.width and vc->vc_rows * vc->vc_font.heigh do not
cause integer overflow.

[1] https://syzkaller.appspot.com/bug?id=a565882df74fa76f10d3a6fec4be31098dbb37c6

Reported-and-tested-by: syzbot 
Signed-off-by: Tetsuo Handa 
Acked-by: Daniel Vetter 
Cc: stable 
Link: https://lore.kernel.org/r/20200715015102.3814-1-penguin-kernel@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman