linux-stable.git/drivers/video/console, branch linux-4.9.y Linux kernel stable tree vgacon: Propagate console boot parameters before calling `vc_resize' 2021-12-08T07:45:06+00:00 Maciej W. Rozycki macro@orcam.me.uk 2021-10-25T22:26:22+00:00 e3de861272cccd8ab75f718ab8432e0ff7899a36 commit 3dfac26e2ef29ff2abc2a75aa4cd48fce25a2c4b upstream. Fix a division by zero in `vgacon_resize' with a backtrace like: vgacon_resize vc_do_resize vgacon_init do_bind_con_driver do_unbind_con_driver fbcon_fb_unbind do_unregister_framebuffer do_register_framebuffer register_framebuffer __drm_fb_helper_initial_config_and_unlock drm_helper_hpd_irq_event dw_hdmi_irq irq_thread kthread caused by `c->vc_cell_height' not having been initialized. This has only started to trigger with commit 860dafa90259 ("vt: Fix character height handling with VT_RESIZEX"), however the ultimate offender is commit 50ec42edd978 ("[PATCH] Detaching fbcon: fix vgacon to allow retaking of the console"). Said commit has added a call to `vc_resize' whenever `vgacon_init' is called with the `init' argument set to 0, which did not happen before. And the call is made before a key vgacon boot parameter retrieved in `vgacon_startup' has been propagated in `vgacon_init' for `vc_resize' to use to the console structure being worked on. Previously the parameter was `c->vc_font.height' and now it is `c->vc_cell_height'. In this particular scenario the registration of fbcon has failed and vt resorts to vgacon. Now fbcon does have initialized `c->vc_font.height' somehow, unlike `c->vc_cell_height', which is why this code did not crash before, but either way the boot parameters should have been copied to the console structure ahead of the call to `vc_resize' rather than afterwards, so that first the call has a chance to use them and second they do not change the console structure to something possibly different from what was used by `vc_resize'. Move the propagation of the vgacon boot parameters ahead of the call to `vc_resize' then. Adjust the comment accordingly. Fixes: 50ec42edd978 ("[PATCH] Detaching fbcon: fix vgacon to allow retaking of the console") Cc: stable@vger.kernel.org # v2.6.18+ Reported-by: Wim Osterholt <wim@djo.tudelft.nl> Reported-by: Pavel V. Panteleev <panteleev_p@mcst.ru> Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Link: https://lore.kernel.org/r/alpine.DEB.2.21.2110252317110.58149@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 3dfac26e2ef29ff2abc2a75aa4cd48fce25a2c4b upstream.

Fix a division by zero in `vgacon_resize' with a backtrace like:

vgacon_resize
vc_do_resize
vgacon_init
do_bind_con_driver
do_unbind_con_driver
fbcon_fb_unbind
do_unregister_framebuffer
do_register_framebuffer
register_framebuffer
__drm_fb_helper_initial_config_and_unlock
drm_helper_hpd_irq_event
dw_hdmi_irq
irq_thread
kthread

caused by `c->vc_cell_height' not having been initialized.  This has
only started to trigger with commit 860dafa90259 ("vt: Fix character
height handling with VT_RESIZEX"), however the ultimate offender is
commit 50ec42edd978 ("[PATCH] Detaching fbcon: fix vgacon to allow
retaking of the console").

Said commit has added a call to `vc_resize' whenever `vgacon_init' is
called with the `init' argument set to 0, which did not happen before.
And the call is made before a key vgacon boot parameter retrieved in
`vgacon_startup' has been propagated in `vgacon_init' for `vc_resize' to
use to the console structure being worked on.  Previously the parameter
was `c->vc_font.height' and now it is `c->vc_cell_height'.

In this particular scenario the registration of fbcon has failed and vt
resorts to vgacon.  Now fbcon does have initialized `c->vc_font.height'
somehow, unlike `c->vc_cell_height', which is why this code did not
crash before, but either way the boot parameters should have been copied
to the console structure ahead of the call to `vc_resize' rather than
afterwards, so that first the call has a chance to use them and second
they do not change the console structure to something possibly different
from what was used by `vc_resize'.

Move the propagation of the vgacon boot parameters ahead of the call to
`vc_resize' then.  Adjust the comment accordingly.

Fixes: 50ec42edd978 ("[PATCH] Detaching fbcon: fix vgacon to allow retaking of the console")
Cc: stable@vger.kernel.org # v2.6.18+
Reported-by: Wim Osterholt <wim@djo.tudelft.nl>
Reported-by: Pavel V. Panteleev <panteleev_p@mcst.ru>
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2110252317110.58149@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
parisc/sticon: fix reverse colors 2021-11-26T10:48:42+00:00 Sven Schnelle svens@stackframe.org 2021-11-14T16:08:17+00:00 92842fc90ca23f3fd3882fdcf0992fae51d71131 commit bec05f33ebc1006899c6d3e59a00c58881fe7626 upstream. sticon_build_attr() checked the reverse argument and flipped background and foreground color, but returned the non-reverse value afterwards. Fix this and also add two local variables for foreground and background color to make the code easier to read. Signed-off-by: Sven Schnelle <svens@stackframe.org> Cc: <stable@vger.kernel.org> Signed-off-by: Helge Deller <deller@gmx.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit bec05f33ebc1006899c6d3e59a00c58881fe7626 upstream.

sticon_build_attr() checked the reverse argument and flipped
background and foreground color, but returned the non-reverse
value afterwards. Fix this and also add two local variables
for foreground and background color to make the code easier
to read.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tty: vt: always invoke vc->vc_sw->con_resize callback 2021-05-26T09:29:09+00:00 Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp 2021-05-15T03:00:37+00:00 51a17f52f297d6a2a09928d72bb00dfcd73a5131 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 <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/ioctl.h> #include <linux/kd.h> #include <linux/vt.h> 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 <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Tested-by: syzbot <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
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 <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #include <sys/ioctl.h>
  #include <linux/kd.h>
  #include <linux/vt.h>

  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 <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Tested-by: syzbot <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
vt: Fix character height handling with VT_RESIZEX 2021-05-26T09:29:08+00:00 Maciej W. Rozycki macro@orcam.me.uk 2021-05-13T09:51:50+00:00 3bd3a8ca5a7b1530f463b6e1cc811c085e6ffa01 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: <git://git.kernel.org/pub/scm/linux/kernel/git/ralf/linux.git> 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 <macro@orcam.me.uk> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org # v2.6.12+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
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: <git://git.kernel.org/pub/scm/linux/kernel/git/ralf/linux.git>
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 <macro@orcam.me.uk>
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org # v2.6.12+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
vgacon: Record video mode changes with VT_RESIZEX 2021-05-26T09:29:08+00:00 Maciej W. Rozycki macro@orcam.me.uk 2021-05-13T09:51:41+00:00 a48e9382cffdd022bd9c448c29265b858133d84d commit d4d0ad57b3865795c4cde2fb5094c594c2e8f469 upstream. Fix an issue with VGA console font size changes made after the initial video text mode has been changed with a user tool like `svgatextmode' calling the VT_RESIZEX ioctl. As it stands in that case the original screen geometry continues being used to validate further VT resizing. Consequently when the video adapter is firstly reprogrammed from the original say 80x25 text mode using a 9x16 character cell (720x400 pixel resolution) to say 80x37 text mode and the same character cell (720x592 pixel resolution), and secondly the CRTC character cell updated to 9x8 (by loading a suitable font with the KD_FONT_OP_SET request of the KDFONTOP ioctl), the VT geometry does not get further updated from 80x37 and only upper half of the screen is used for the VT, with the lower half showing rubbish corresponding to whatever happens to be there in the video memory that maps to that part of the screen. Of course the proportions change according to text mode geometries and font sizes chosen. Address the problem then, by updating the text mode geometry defaults rather than checking against them whenever the VT is resized via a user ioctl. Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Fixes: e400b6ec4ede ("vt/vgacon: Check if screen resize request comes from userspace") Cc: stable@vger.kernel.org # v2.6.24+ Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d4d0ad57b3865795c4cde2fb5094c594c2e8f469 upstream.

Fix an issue with VGA console font size changes made after the initial
video text mode has been changed with a user tool like `svgatextmode'
calling the VT_RESIZEX ioctl.  As it stands in that case the original
screen geometry continues being used to validate further VT resizing.

Consequently when the video adapter is firstly reprogrammed from the
original say 80x25 text mode using a 9x16 character cell (720x400 pixel
resolution) to say 80x37 text mode and the same character cell (720x592
pixel resolution), and secondly the CRTC character cell updated to 9x8
(by loading a suitable font with the KD_FONT_OP_SET request of the
KDFONTOP ioctl), the VT geometry does not get further updated from 80x37
and only upper half of the screen is used for the VT, with the lower
half showing rubbish corresponding to whatever happens to be there in
the video memory that maps to that part of the screen.  Of course the
proportions change according to text mode geometries and font sizes
chosen.

Address the problem then, by updating the text mode geometry defaults
rather than checking against them whenever the VT is resized via a user
ioctl.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Fixes: e400b6ec4ede ("vt/vgacon: Check if screen resize request comes from userspace")
Cc: stable@vger.kernel.org # v2.6.24+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fbcon: Fix global-out-of-bounds read in fbcon_get_font() 2020-10-14T07:48:14+00:00 Peilin Ye yepeilin.cs@gmail.com 2020-09-24T13:43:48+00:00 6f1adb22fc0c567d65e8c56cc04d633d2fa1bfb4 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 <yepeilin.cs@gmail.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/b34544687a1a09d6de630659eb7a773f4953238b.1600953813.git.yepeilin.cs@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
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 <yepeilin.cs@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/b34544687a1a09d6de630659eb7a773f4953238b.1600953813.git.yepeilin.cs@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fbdev, newport_con: Move FONT_EXTRA_WORDS macros into linux/font.h 2020-10-14T07:48:14+00:00 Peilin Ye yepeilin.cs@gmail.com 2020-09-24T13:40:53+00:00 8ab047585733025fd136331365c74e1b0282ac43 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 <linux/font.h>. 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 <yepeilin.cs@gmail.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/7fb8bc9b0abc676ada6b7ac0e0bd443499357267.1600953813.git.yepeilin.cs@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
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 <linux/font.h>.

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 <yepeilin.cs@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/7fb8bc9b0abc676ada6b7ac0e0bd443499357267.1600953813.git.yepeilin.cs@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fbcon: Fix user font detection test at fbcon_resize(). 2020-09-23T06:46:15+00:00 Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp 2020-09-10T22:57:06+00:00 f9300df2f7add904ee364f358e07097946c0b42a [ 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 <syzbot+b38b1ef6edf0c74a8d97@syzkaller.appspotmail.com> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Fixes: 39b3cffb8cf31117 ("fbcon: prevent user font height or width change from causing potential out-of-bounds access") Cc: George Kennedy <george.kennedy@oracle.com> Link: https://lore.kernel.org/r/f6e3e611-8704-1263-d163-f52c906a4f06@I-love.SAKURA.ne.jp Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ 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 <syzbot+b38b1ef6edf0c74a8d97@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Fixes: 39b3cffb8cf31117 ("fbcon: prevent user font height or width change from causing potential out-of-bounds access")
Cc: George Kennedy <george.kennedy@oracle.com>
Link: https://lore.kernel.org/r/f6e3e611-8704-1263-d163-f52c906a4f06@I-love.SAKURA.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
vgacon: remove software scrollback support 2020-09-23T06:46:13+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-09-09T21:53:50+00:00 7cabb35d2106d567af15ea1040c7737f34b29cd8 commit 973c096f6a85e5b5f2a295126ba6928d9a6afd45 upstream. Yunhai Zhang recently fixed a VGA software scrollback bug in commit ebfdfeeae8c0 ("vgacon: Fix for missing check in scrollback handling"), but that then made people look more closely at some of this code, and there were more problems on the vgacon side, but also the fbcon software scrollback. We don't really have anybody who maintains this code - probably because nobody actually _uses_ it any more. Sure, people still use both VGA and the framebuffer consoles, but they are no longer the main user interfaces to the kernel, and haven't been for decades, so these kinds of extra features end up bitrotting and not really being used. So rather than try to maintain a likely unused set of code, I'll just aggressively remove it, and see if anybody even notices. Maybe there are people who haven't jumped on the whole GUI badnwagon yet, and think it's just a fad. And maybe those people use the scrollback code. If that turns out to be the case, we can resurrect this again, once we've found the sucker^Wmaintainer for it who actually uses it. Reported-by: NopNop Nop <nopitydays@gmail.com> Tested-by: Willy Tarreau <w@1wt.eu> Cc: 张云海 <zhangyunhai@nsfocus.com> Acked-by: Andy Lutomirski <luto@amacapital.net> Acked-by: Willy Tarreau <w@1wt.eu> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 973c096f6a85e5b5f2a295126ba6928d9a6afd45 upstream.

Yunhai Zhang recently fixed a VGA software scrollback bug in commit
ebfdfeeae8c0 ("vgacon: Fix for missing check in scrollback handling"),
but that then made people look more closely at some of this code, and
there were more problems on the vgacon side, but also the fbcon software
scrollback.

We don't really have anybody who maintains this code - probably because
nobody actually _uses_ it any more.  Sure, people still use both VGA and
the framebuffer consoles, but they are no longer the main user
interfaces to the kernel, and haven't been for decades, so these kinds
of extra features end up bitrotting and not really being used.

So rather than try to maintain a likely unused set of code, I'll just
aggressively remove it, and see if anybody even notices.  Maybe there
are people who haven't jumped on the whole GUI badnwagon yet, and think
it's just a fad.  And maybe those people use the scrollback code.

If that turns out to be the case, we can resurrect this again, once
we've found the sucker^Wmaintainer for it who actually uses it.

Reported-by: NopNop Nop <nopitydays@gmail.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Cc: 张云海 <zhangyunhai@nsfocus.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fbcon: remove now unusued 'softback_lines' cursor() argument 2020-09-23T06:46:12+00:00 Linus Torvalds torvalds@linux-foundation.org 2020-09-08T17:56:27+00:00 84175ff8a2886aa606211b16c0024d08e06c9a4f commit 06a0df4d1b8b13b551668e47b11fd7629033b7df upstream. Since the softscroll code got removed, this argument is always zero and makes no sense any more. Tested-by: Yuan Ming <yuanmingbuaa@gmail.com> Tested-by: Willy Tarreau <w@1wt.eu> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 06a0df4d1b8b13b551668e47b11fd7629033b7df upstream.

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

Tested-by: Yuan Ming <yuanmingbuaa@gmail.com>
Tested-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>