linux-stable.git/drivers/tty/vt, branch linux-4.9.y

vt: Clear selection before changing the font

2022-09-15T10:39:44+00:00

commit 566f9c9f89337792070b5a6062dff448b3e7977f upstream.

When changing the console font with ioctl(KDFONTOP) the new font size
can be bigger than the previous font. A previous selection may thus now
be outside of the new screen size and thus trigger out-of-bounds
accesses to graphics memory if the selection is removed in
vc_do_resize().

Prevent such out-of-memory accesses by dropping the selection before the
various con_font_set() console handlers are called.

Reported-by: syzbot+14b0e8f3fd1612e35350@syzkaller.appspotmail.com
Cc: stable 
Tested-by: Khalid Masum 
Signed-off-by: Helge Deller 
Link: https://lore.kernel.org/r/YuV9apZGNmGfjcor@p100
Signed-off-by: Greg Kroah-Hartman

tty: drivers/tty/, stop using tty_schedule_flip()

2022-07-29T15:05:47+00:00

commit 5f6a85158ccacc3f09744b3aafe8b11ab3b6c6f6 upstream.

Since commit a9c3f68f3cd8d (tty: Fix low_latency BUG) in 2014,
tty_flip_buffer_push() is only a wrapper to tty_schedule_flip(). We are
going to remove the latter (as it is used less), so call the former in
drivers/tty/.

Cc: Vladimir Zapolskiy 
Reviewed-by: Johan Hovold 
Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20211122111648.30379-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman

vt: drop old FONT ioctls

2022-07-02T14:17:14+00:00

commit ff2047fb755d4415ec3c70ac799889371151796d upstream.

Drop support for these ioctls:
* PIO_FONT, PIO_FONTX
* GIO_FONT, GIO_FONTX
* PIO_FONTRESET

As was demonstrated by commit 90bfdeef83f1 (tty: make FONTX ioctl use
the tty pointer they were actually passed), these ioctls are not used
from userspace, as:
1) they used to be broken (set up font on current console, not the open
   one) and racy (before the commit above)
2) KDFONTOP ioctl is used for years instead

Note that PIO_FONTRESET is defunct on most systems as VGA_CONSOLE is set
on them for ages. That turns on BROKEN_GRAPHICS_PROGRAMS which makes
PIO_FONTRESET just return an error.

We are removing KD_FONT_FLAG_OLD here as it was used only by these
removed ioctls. kd.h header exists both in kernel and uapi headers, so
we can remove the kernel one completely. Everyone includeing kd.h will
now automatically get the uapi one.

There are now unused definitions of the ioctl numbers and "struct
consolefontdesc" in kd.h, but as it is a uapi header, I am not touching
these.

Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20210105120239.28031-8-jslaby@suse.cz
Cc: guodaxing 
Signed-off-by: Greg Kroah-Hartman

vt_ioctl: add array_index_nospec to VT_ACTIVATE

2022-02-16T11:43:54+00:00

commit 28cb138f559f8c1a1395f5564f86b8bbee83631b upstream.

in vt_setactivate an almost identical code path has been patched
with array_index_nospec. In the VT_ACTIVATE path the user input
is from a system call argument instead of a usercopy.
For consistency both code paths should have the same mitigations
applied.

Kasper Acknowledgements: Jakob Koschel, Brian Johannesmeyer, Kaveh
Razavi, Herbert Bos, Cristiano Giuffrida from the VUSec group at VU
Amsterdam.

Co-developed-by: Brian Johannesmeyer 
Signed-off-by: Brian Johannesmeyer 
Signed-off-by: Jakob Koschel 
Link: https://lore.kernel.org/r/20220127144406.3589293-2-jakobkoschel@gmail.com
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

vt_ioctl: fix array_index_nospec in vt_setactivate

2022-02-16T11:43:54+00:00

commit 61cc70d9e8ef5b042d4ed87994d20100ec8896d9 upstream.

array_index_nospec ensures that an out-of-bounds value is set to zero
on the transient path. Decreasing the value by one afterwards causes
a transient integer underflow. vsa.console should be decreased first
and then sanitized with array_index_nospec.

Kasper Acknowledgements: Jakob Koschel, Brian Johannesmeyer, Kaveh
Razavi, Herbert Bos, Cristiano Giuffrida from the VUSec group at VU
Amsterdam.

Co-developed-by: Brian Johannesmeyer 
Signed-off-by: Brian Johannesmeyer 
Signed-off-by: Jakob Koschel 
Link: https://lore.kernel.org/r/20220127144406.3589293-1-jakobkoschel@gmail.com
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

tty: Fix out-of-bound vmalloc access in imageblit

2021-10-06T08:23:41+00:00

[ Upstream commit 3b0c406124719b625b1aba431659f5cdc24a982c ]

This issue happens when a userspace program does an ioctl
FBIOPUT_VSCREENINFO passing the fb_var_screeninfo struct
containing only the fields xres, yres, and bits_per_pixel
with values.

If this struct is the same as the previous ioctl, the
vc_resize() detects it and doesn't call the resize_screen(),
leaving the fb_var_screeninfo incomplete. And this leads to
the updatescrollmode() calculates a wrong value to
fbcon_display->vrows, which makes the real_y() return a
wrong value of y, and that value, eventually, causes
the imageblit to access an out-of-bound address value.

To solve this issue I made the resize_screen() be called
even if the screen does not need any resizing, so it will
"fix and fill" the fb_var_screeninfo independently.

Cc: stable  # after 5.15-rc2 is out, give it time to bake
Reported-and-tested-by: syzbot+858dc7a2f7ef07c2c219@syzkaller.appspotmail.com
Signed-off-by: Igor Matheus Andrade Torrente 
Link: https://lore.kernel.org/r/20210628134509.15895-1-igormtorrente@gmail.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

vt_kdsetmode: extend console locking

2021-09-03T07:44:40+00:00

commit 2287a51ba822384834dafc1c798453375d1107c7 upstream.

As per the long-suffering comment.

Reported-by: Minh Yuan 
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

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

2021-05-26T09:29:09+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

vt: Fix character height handling with VT_RESIZEX

2021-05-26T09:29:08+00:00

commit 860dafa902595fb5f1d23bbcce1215188c3341e6 upstream.

Restore the original intent of the VT_RESIZEX ioctl's `v_clin' parameter
which is the number of pixel rows per character (cell) rather than the
height of the font used.

For framebuffer devices the two values are always the same, because the
former is inferred from the latter one.  For VGA used as a true text
mode device these two parameters are independent from each other: the
number of pixel rows per character is set in the CRT controller, while
font height is in fact hardwired to 32 pixel rows and fonts of heights
below that value are handled by padding their data with blanks when
loaded to hardware for use by the character generator.  One can change
the setting in the CRT controller and it will update the screen contents
accordingly regardless of the font loaded.

The `v_clin' parameter is used by the `vgacon' driver to set the height
of the character cell and then the cursor position within.  Make the
parameter explicit then, by defining a new `vc_cell_height' struct
member of `vc_data', set it instead of `vc_font.height' from `v_clin' in
the VT_RESIZEX ioctl, and then use it throughout the `vgacon' driver
except where actual font data is accessed which as noted above is
independent from the CRTC setting.

This way the framebuffer console driver is free to ignore the `v_clin'
parameter as irrelevant, as it always should have, avoiding any issues
attempts to give the parameter a meaning there could have caused, such
as one that has led to commit 988d0763361b ("vt_ioctl: make VT_RESIZEX
behave like VT_RESIZE"):

 "syzbot is reporting UAF/OOB read at bit_putcs()/soft_cursor() [1][2],
  for vt_resizex() from ioctl(VT_RESIZEX) allows setting font height
  larger than actual font height calculated by con_font_set() from
  ioctl(PIO_FONT). Since fbcon_set_font() from con_font_set() allocates
  minimal amount of memory based on actual font height calculated by
  con_font_set(), use of vt_resizex() can cause UAF/OOB read for font
  data."

The problem first appeared around Linux 2.5.66 which predates our repo
history, but the origin could be identified with the old MIPS/Linux repo
also at: 
as commit 9736a3546de7 ("Merge with Linux 2.5.66."), where VT_RESIZEX
code in `vt_ioctl' was updated as follows:

 		if (clin)
-			video_font_height = clin;
+			vc->vc_font.height = clin;

making the parameter apply to framebuffer devices as well, perhaps due
to the use of "font" in the name of the original `video_font_height'
variable.  Use "cell" in the new struct member then to avoid ambiguity.

References:

[1] https://syzkaller.appspot.com/bug?id=32577e96d88447ded2d3b76d71254fb855245837
[2] https://syzkaller.appspot.com/bug?id=6b8355d27b2b94fb5cedf4655e3a59162d9e48e3

Signed-off-by: Maciej W. Rozycki 
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org # v2.6.12+
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

vt/consolemap: do font sum unsigned

2021-03-07T10:25:57+00:00

[ Upstream commit 9777f8e60e718f7b022a94f2524f967d8def1931 ]

The constant 20 makes the font sum computation signed which can lead to
sign extensions and signed wraps. It's not much of a problem as we build
with -fno-strict-overflow. But if we ever decide not to, be ready, so
switch the constant to unsigned.

Signed-off-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20210105120239.28031-7-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin