Merge VT_RESIZEX fixes from Maciej Rozycki:
"I got to the bottom of the issue with VT_RESIZEX recently discussed
and came up with this small patch series, fixing an additional issue
that I originally thought might be broken VGA hardware emulation with
my laptop, which however turned out to be intertwined with the
original problem and also a regression introduced somewhat later.
The fix for that because the first patch, and then to make backporting
feasible I had to put a revert of the offending change from last
September next, followed by a proper fix for the framebuffer issue
that change had tried to address.
See individual change descriptions for details.
These have been verified with true VGA hardware (a Trident TVGA8900
ISA video adapter) using various combinations of `svgatextmode' and
`setfont' command invocations to change both the VT size and the font
size, and also switching between the text console and X11, both by
starting/stopping the X server and by switching between VTs.
All this to ensure bringing the behaviour of VGA text console back to
correct operation as it used to be with Linux 2.6.18"
* emailed patches from Maciej W. Rozycki <macro@orcam.me.uk>:
vt: Fix character height handling with VT_RESIZEX
vt_ioctl: Revert VT_RESIZEX parameter handling removal
vgacon: Record video mode changes with VT_RESIZEX
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 988d076336 ("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: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org # v2.6.12+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Revert the removal of code handling extra VT_RESIZEX ioctl's parameters
beyond those that VT_RESIZE supports, fixing a functional regression
causing `svgatextmode' not to resize the VT anymore.
As a consequence of the reverted change when the video adapter is
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), the VT geometry does not
get updated and only upper two thirds of the screen are used for the VT,
and the lower part remains blank. The proportions change according to
text mode geometries chosen.
Revert the change verbatim then, bringing back previous VT resizing.
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Fixes: 988d076336 ("vt_ioctl: make VT_RESIZEX behave like VT_RESIZE")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The pattern prefixed with '/' matches files in the same directory,
but not ones in sub-directories.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Andra Paraschiv <andraprs@amazon.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Gabriel Krisman Bertazi <krisman@collabora.com>
syzbot reported memory leak in tty/vt.
The problem was in VT_DISALLOCATE ioctl cmd.
After allocating unimap with PIO_UNIMAP it wasn't
freed via VT_DISALLOCATE, but vc_cons[currcons].d was
zeroed.
Reported-by: syzbot+bcc922b19ccc64240b42@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210327214443.21548-1-paskripkin@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Kernel documentation validator is not happy:
.../keyboard.c:2195: warning: expecting prototype for vt_get_shiftstate(). Prototype was for vt_get_shift_state() instead
This is due to typo, fix it here.
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210303083229.75784-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
reset_vc() uses a "!in_interrupt()" conditional before resetting the
palettes, which is a blocking operation. Since commit
8b6312f4dc ("[PATCH] vt: refactor console SAK processing")
all calls are invoked from a workqueue process context, with the
blocking console lock always acquired.
Remove the "!in_interrupt()" check.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/20210208181615.381861-2-bigeasy@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This converts the keyboard_tasklet to use the new API in
commit 12cc923f1c ("tasklet: Introduce new initialization API")
The new API changes the argument passed to the callback function, but
fortunately the argument isn't used so it is straight forward to use
DECLARE_TASKLET_DISABLED() rather than DECLARE_TASKLET_DISABLED_OLD().
Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Link: https://lore.kernel.org/r/20210127164222.13220-1-kernel@esmil.dk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Drop support for these ioctls:
* PIO_FONT, PIO_FONTX
* GIO_FONT, GIO_FONTX
* PIO_FONTRESET
As was demonstrated by commit 90bfdeef83 (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 <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-8-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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 <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-7-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Commit 5ce2087ed0 (Fix default compose table initialization) fixed
unicode table so that the values are not sign extended. The upstream
(kbd package) chose a different approach. They use hexadecimal values.
So use the same, so that the output of loadkeys and our shipped file
correspond more to each other.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-4-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
loadkeys (from kbd) generates 'unsigned short' instead of 'u_short'
since 2.0.3. It also marks maps as 'static' for longer than kbd's
history.
So adapt the shipped defkeymap.c to conform more to loadkeys output.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Now that the last extern user of the tasklet (set_leds) is in
keyboard.c, we can make keyboard_tasklet local to this unit too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
set_leds and compute_shiftstate are called from a single place in vt.c.
Let's combine these two into vt_set_leds_compute_shiftstate. This allows
for making keyboard_tasklet local in the next patch.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20210105120239.28031-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We have for some time the assign_bit() API to replace open coded
if (foo)
set_bit(n, bar);
else
clear_bit(n, bar);
Use this API in VT keyboard library code.
Acked-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20201109105601.47159-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here are a small number of small tty and serial fixes for some reported
problems for the tty core, vt code, and some serial drivers.
They include fixes for:
- a buggy and obsolete vt font ioctl removal
- 8250_mtk serial baudrate runtime warnings
- imx serial earlycon build configuration fix
- txx9 serial driver error path cleanup issues
- tty core fix in release_tty that can be triggered by trying to
bind an invalid serial port name to a speakup console device
Almost all of these have been in linux-next without any problems, the
only one that hasn't, just deletes code :)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-5.10-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial fixes from Greg KH:
"Here are a small number of small tty and serial fixes for some
reported problems for the tty core, vt code, and some serial drivers.
They include fixes for:
- a buggy and obsolete vt font ioctl removal
- 8250_mtk serial baudrate runtime warnings
- imx serial earlycon build configuration fix
- txx9 serial driver error path cleanup issues
- tty core fix in release_tty that can be triggered by trying to bind
an invalid serial port name to a speakup console device
Almost all of these have been in linux-next without any problems, the
only one that hasn't, just deletes code :)"
* tag 'tty-5.10-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
vt: Disable KD_FONT_OP_COPY
tty: fix crash in release_tty if tty->port is not set
serial: txx9: add missing platform_driver_unregister() on error in serial_txx9_init
tty: serial: imx: enable earlycon by default if IMX_SERIAL_CONSOLE is enabled
serial: 8250_mtk: Fix uart_get_baud_rate warning
It's buggy:
On Fri, Nov 06, 2020 at 10:30:08PM +0800, Minh Yuan wrote:
> We recently discovered a slab-out-of-bounds read in fbcon in the latest
> kernel ( v5.10-rc2 for now ). The root cause of this vulnerability is that
> "fbcon_do_set_font" did not handle "vc->vc_font.data" and
> "vc->vc_font.height" correctly, and the patch
> <https://lkml.org/lkml/2020/9/27/223> for VT_RESIZEX can't handle this
> issue.
>
> Specifically, we use KD_FONT_OP_SET to set a small font.data for tty6, and
> use KD_FONT_OP_SET again to set a large font.height for tty1. After that,
> we use KD_FONT_OP_COPY to assign tty6's vc_font.data to tty1's vc_font.data
> in "fbcon_do_set_font", while tty1 retains the original larger
> height. Obviously, this will cause an out-of-bounds read, because we can
> access a smaller vc_font.data with a larger vc_font.height.
Further there was only one user ever.
- Android's loadfont, busybox and console-tools only ever use OP_GET
and OP_SET
- fbset documentation only mentions the kernel cmdline font: option,
not anything else.
- systemd used OP_COPY before release 232 published in Nov 2016
Now unfortunately the crucial report seems to have gone down with
gmane, and the commit message doesn't say much. But the pull request
hints at OP_COPY being broken
https://github.com/systemd/systemd/pull/3651
So in other words, this never worked, and the only project which
foolishly every tried to use it, realized that rather quickly too.
Instead of trying to fix security issues here on dead code by adding
missing checks, fix the entire thing by removing the functionality.
Note that systemd code using the OP_COPY function ignored the return
value, so it doesn't matter what we're doing here really - just in
case a lone server somewhere happens to be extremely unlucky and
running an affected old version of systemd. The relevant code from
font_copy_to_all_vcs() in systemd was:
/* copy font from active VT, where the font was uploaded to */
cfo.op = KD_FONT_OP_COPY;
cfo.height = vcs.v_active-1; /* tty1 == index 0 */
(void) ioctl(vcfd, KDFONTOP, &cfo);
Note this just disables the ioctl, garbage collecting the now unused
callbacks is left for -next.
v2: Tetsuo found the old mail, which allowed me to find it on another
archive. Add the link too.
Acked-by: Peilin Ye <yepeilin.cs@gmail.com>
Reported-by: Minh Yuan <yuanmingbuaa@gmail.com>
References: https://lists.freedesktop.org/archives/systemd-devel/2016-June/036935.html
References: https://github.com/systemd/systemd/pull/3651
Cc: Greg KH <greg@kroah.com>
Cc: Peilin Ye <yepeilin.cs@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://lore.kernel.org/r/20201108153806.3140315-1-daniel.vetter@ffwll.ch
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes the following W=1 kernel build warning(s):
drivers/tty/vt/consolemap.c:739: warning: Function parameter or member 'ct' not described in 'con_get_unimap'
drivers/tty/vt/consolemap.c:739: warning: Function parameter or member 'uct' not described in 'con_get_unimap'
drivers/tty/vt/consolemap.c:739: warning: Function parameter or member 'list' not described in 'con_get_unimap'
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Jakub Jelinek <jj@ultra.linux.cz>
Cc: Stanislav Voronyi <stas@cnti.uanet.kharkov.ua>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201104193549.4026187-10-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
'puts_queue' currently loops over characters and employs the full tty
buffer machinery for every character. Do the buffer allocation only once
and copy all the character at once. This is achieved using
tty_insert_flip_string instead of loop+tty_insert_flip_char.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-17-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of a 'for' loop with 'test_bit's to find a bit in a range, use
find_next_bit to achieve the same in a simpler and faster manner.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-16-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Instead of a multiline macro, convert HW_RAW to an inline function. It
allows for type checking of the parameter. And given we split the code
into two tests, it is now more readable too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-15-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Do the permission check on a single place. That is where perm is
really checked.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-14-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Setting of function key strings is now very complex. It uses a global
buffer 'func_buf' which is prefilled in defkeymap.c_shipped. Then there
is also an index table called 'func_table'. So initially, we have
something like this:
char func_buf[] = "\e[[A\0" // for F1
"\e[[B\0" // for F2
...;
char *func_table[] = {
func_buf + 0, // for F1
func_buf + 5, // for F2
... }
When a user changes some specific func string by KDSKBSENT, it is
changed in 'func_buf'. If it is shorter or equal to the current one, it
is handled by a very quick 'strcpy'.
When the user's string is longer, the whole 'func_buf' is reallocated to
allow expansion somewhere in the middle. The buffer before the user's
string is copied, the user's string appended and the rest appended too.
Now, the index table (func_table) needs to be recomputed, of course.
One more complication is the held spinlock -- we have to unlock,
reallocate, lock again and do the whole thing again to be sure noone
raced with us.
In this patch, we chose completely orthogonal approach: when the user's
string is longer than the current one, we simply assign the 'kstrdup'ed
copy to the index table (func_table) and modify func_buf in no way. We
only need to make sure we free the old entries. So we need a bitmap
is_kmalloc and free the old entries (but not the original func_buf
rodata string).
Also note that we do not waste so much space as previous approach. We
only allocate space for single entries which are longer, while before,
the whole buffer was duplicated plus space for the longer string.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-12-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
KDGKBSENT (the getter) needs only 'user_kdgkb->kb_func' from the
userspace, i.e. the index. Then it needs a buffer for a local copy of
'kb_string'.
KDSKBSENT (the setter) needs a copy up to the length of
'user_kdgkb->kb_string'.
That means, we obtain the index before the switch-case and use it in
both paths and:
1) allocate full space in the getter case, and
2) copy the string only in the setter case. We do it by strndup_user
helper now which was not available when this function was written.
Given we copy the two members of 'struct kbsentry' separately, we no
longer need a local definition. Hence we need to change all the sizeofs
here too.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-11-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are too many one-letter variables in vt_do_kdgkb_ioctl which is
rather confusing. Rename 'i' to 'kb_func' and change its type to be the
same as its originating value (struct kbsentry.kb_func) -- unsigned
char.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-10-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
key_down is sued as a bitmap using test_bit, set_bit and similar.
So declare it using DECLARE_BITMAP to make it obvious even from the
declaration.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-8-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Do the permission check on a single place. That is where perm is really
checked.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-7-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Split vt_do_kdsk_ioctl into three functions:
* getter (KDGKBENT/vt_kdgkbent)
* setter (KDSKBENT/vt_kdskbent)
* switch-case helper (vt_do_kdsk_ioctl)
This eliminates the need of ugly one-letter macros as we use parameters
now:
* i aka tmp.kb_index -> idx
* s aka tmp.kb_table -> map
* v aka tmp.kb_value -> val
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-6-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Define one limit per line and index them by their index, so that it is
clear what is what.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-5-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are many includes and it is hard to check if something is there or
not. So sort them alphabetically.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-3-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
We use spin locks, but don't include linux/spinlock.h in keyboards.c. So
fix this up.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ctrl_alt_del is already declared in linux/reboot.h which we include. So
remove this second (superfluous) declaration.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201029113222.32640-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some of the font tty ioctl's always used the current foreground VC for
their operations. Don't do that then.
This fixes a data race on fg_console.
Side note: both Michael Ellerman and Jiri Slaby point out that all these
ioctls are deprecated, and should probably have been removed long ago,
and everything seems to be using the KDFONTOP ioctl instead.
In fact, Michael points out that it looks like busybox's loadfont
program seems to have switched over to using KDFONTOP exactly _because_
of this bug (ahem.. 12 years ago ;-).
Reported-by: Minh Yuan <yuanmingbuaa@gmail.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Jiri Slaby <jirislaby@kernel.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit 5ba1278787, we shuffled with the check of 'perm'. But my
brain somehow inverted the condition in 'do_unimap_ioctl' (I thought
it is ||, not &&), so GIO_UNIMAP stopped working completely.
Move the 'perm' checks back to do_unimap_ioctl and do them right again.
In fact, this reverts this part of code to the pre-5ba127878722 state.
Except 'perm' is now a bool.
Fixes: 5ba1278787 ("vt_ioctl: move perm checks level up")
Cc: stable@vger.kernel.org
Reported-by: Fabian Vogt <fvogt@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201026055419.30518-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Both read-side users of func_table/func_buf need locking. Without that,
one can easily confuse the code by repeatedly setting altering strings
like:
while (1)
for (a = 0; a < 2; a++) {
struct kbsentry kbs = {};
strcpy((char *)kbs.kb_string, a ? ".\n" : "88888\n");
ioctl(fd, KDSKBSENT, &kbs);
}
When that program runs, one can get unexpected output by holding F1
(note the unxpected period on the last line):
.
88888
.8888
So protect all accesses to 'func_table' (and func_buf) by preexisting
'func_buf_lock'.
It is easy in 'k_fn' handler as 'puts_queue' is expected not to sleep.
On the other hand, KDGKBSENT needs a local (atomic) copy of the string
because copy_to_user can sleep. Use already allocated, but unused
'kbs->kb_string' for that purpose.
Note that the program above needs at least CAP_SYS_TTY_CONFIG.
This depends on the previous patch and on the func_buf_lock lock added
in commit 46ca3f735f (tty/vt: fix write/write race in ioctl(KDSKBSENT)
handler) in 5.2.
Likely fixes CVE-2020-25656.
Cc: <stable@vger.kernel.org>
Reported-by: Minh Yuan <yuanmingbuaa@gmail.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201019085517.10176-2-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Use 'strlen' of the string, add one for NUL terminator and simply do
'copy_to_user' instead of the explicit 'for' loop. This makes the
KDGKBSENT case more compact.
The only thing we need to take care about is NULL 'func_table[i]'. Use
an empty string in that case.
The original check for overflow could never trigger as the func_buf
strings are always shorter or equal to 'struct kbsentry's.
Cc: <stable@vger.kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201019085517.10176-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.
VT_RESIZEX was introduced in Linux 1.3.3, but it is unclear that what
comes to the "+ more" part, and I couldn't find a user of VT_RESIZEX.
#define VT_RESIZE 0x5609 /* set kernel's idea of screensize */
#define VT_RESIZEX 0x560A /* set kernel's idea of screensize + more */
So far we are not aware of syzbot reports caused by setting non-zero value
to v_vlin parameter. But given that it is possible that nobody is using
VT_RESIZEX, we can try removing support for v_clin and v_vlin parameters.
Therefore, this patch effectively makes VT_RESIZEX behave like VT_RESIZE,
with emitting a message if somebody is still using v_clin and/or v_vlin
parameters.
[1] https://syzkaller.appspot.com/bug?id=32577e96d88447ded2d3b76d71254fb855245837
[2] https://syzkaller.appspot.com/bug?id=6b8355d27b2b94fb5cedf4655e3a59162d9e48e3
Reported-by: syzbot <syzbot+b308f5fd049fbbc6e74f@syzkaller.appspotmail.com>
Reported-by: syzbot <syzbot+16469b5e8e5a72e9131e@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/4933b81b-9b1a-355b-df0e-9b31e8280ab9@i-love.sakura.ne.jp
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge 5.9-rc3 into tty-next
We need the tty/serial fixes in here as well.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Here are a few small TTY/Serial/vt fixes for 5.9-rc3
Included in here are:
- qcom serial fixes
- vt ioctl and core bugfixes
- pl011 serial driver fixes
- 8250 serial driver fixes
- other misc serial driver fixes
and for good measure:
- fbcon fix for syzbot found problem.
All of these have been in linux-next for a while with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-5.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/serial fixes from Greg KH:
"Here are a few small TTY/Serial/vt fixes for 5.9-rc3
Included in here are:
- qcom serial fixes
- vt ioctl and core bugfixes
- pl011 serial driver fixes
- 8250 serial driver fixes
- other misc serial driver fixes
and for good measure:
- fbcon fix for syzbot found problem.
All of these have been in linux-next for a while with no reported
issues"
* tag 'tty-5.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
tty: serial: imx: add dependence and build for earlycon
serial: samsung: Removes the IRQ not found warning
serial: 8250: change lock order in serial8250_do_startup()
serial: stm32: avoid kernel warning on absence of optional IRQ
serial: pl011: Fix oops on -EPROBE_DEFER
serial: pl011: Don't leak amba_ports entry on driver register error
serial: 8250_exar: Fix number of ports for Commtech PCIe cards
tty: serial: qcom_geni_serial: Drop __init from qcom_geni_console_setup
serial: qcom_geni_serial: Fix recent kdb hang
vt_ioctl: change VT_RESIZEX ioctl to check for error return from vc_resize()
fbcon: prevent user font height or width change from causing potential out-of-bounds access
vt: defer kfree() of vc_screenbuf in vc_do_resize()
This reverts commit b1c32fcfad, because
Syzkaller reports a use-after-free, a write in vcs_read:
BUG: KASAN: use-after-free in vcs_read_buf drivers/tty/vt/vc_screen.c:357 [inline]
BUG: KASAN: use-after-free in vcs_read+0xaa7/0xb40 drivers/tty/vt/vc_screen.c:449
Write of size 2 at addr ffff8880a8014000 by task syz-executor.5/16936
CPU: 1 PID: 16936 Comm: syz-executor.5 Not tainted 5.9.0-rc1-next-20200820-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
...
kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
vcs_read_buf drivers/tty/vt/vc_screen.c:357 [inline]
vcs_read+0xaa7/0xb40 drivers/tty/vt/vc_screen.c:449
There are two issues with the patch:
1) vcs_read rounds the 'count' *up* to an even number. So if we read odd
bytes from the header (3 bytes in the reproducer), the second byte of
a (2-byte/ushort) write to temporary con_buf won't fit. It is because
with the patch applied, we only subtract the real number read (3 bytes)
and not the whole header (4 bytes).
2) in this scenario, we perform unaligned accesses now: there are
2-byte/ushort writes to odd addresses. Due to the same reason as
above.
Revert this for now, re-think and retry later.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Reported-by: syzbot+ad1f53726c3bd11180cb@syzkaller.appspotmail.com
Fixes: b1c32fcfad ("vc_screen: extract vcs_read_buf_header")
Cc: akpm@linux-foundation.org
Cc: nico@fluxnic.net
Link: https://lore.kernel.org/r/20200824095425.4376-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Do not undefine random words. I guess this was here as there were macros
with such generic names somewhere. I very doubt they still exist. So
drop these.
And remove a spare blank line.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20200818085706.12163-16-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tetsuo Handa