The patch titled
Subject: twist: allow disabling k_spec() function in drivers/tty/vt/keyboard.c
has been added to the -mm tree. Its filename is
twist-allow-disabling-k_spec-function-in-drivers-tty-vt-keyboardc.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/twist-allow-disabling-k_spec-function-in-drivers-tty-vt-keyboardc.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/twist-allow-disabling-k_spec-function-in-drivers-tty-vt-keyboardc.patch
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------------------------------------------------------
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Subject: twist: allow disabling k_spec() function in drivers/tty/vt/keyboard.c
syzbot is reporting unexpected kernel reboots [1]. This seems to be
caused by triggering Ctrl-Alt-Del event via k_spec() function in
drivers/tty/vt/keyboard.c file, for the console output includes normal
restart sequence.
[ 97.727327][ T1] systemd-shutdown[1]: Unmounting file systems.
[ 97.734278][ T1] systemd-shutdown[1]: Remounting '/' read-only with options ''.
[ 97.747758][ T21] usb 2-1: device descriptor read/8, error -71
[ 97.747850][ T3116] usb 1-1: device descriptor read/8, error -71
[ 97.764818][ T1] EXT4-fs (sda1): re-mounted. Opts:
[ 97.777551][ T1] systemd-shutdown[1]: Remounting '/' read-only with options ''.
[ 97.785448][ T1] EXT4-fs (sda1): re-mounted. Opts:
[ 97.790920][ T1] systemd-shutdown[1]: All filesystems unmounted.
[ 97.797352][ T1] systemd-shutdown[1]: Deactivating swaps.
[ 97.803451][ T1] systemd-shutdown[1]: All swaps deactivated.
[ 97.809626][ T1] systemd-shutdown[1]: Detaching loop devices.
[ 97.890294][ T1] systemd-shutdown[1]: All loop devices detached.
[ 98.967832][ T3116] usb 1-1: device descriptor read/8, error -71
[ 100.108406][ T1] sd 0:0:1:0: [sda] Synchronizing SCSI cache
[ 100.116036][ T1] reboot: Restarting system
[ 100.120636][ T1] reboot: machine restart
SeaBIOS (version 1.8.2-20200402_173431-google)
Total RAM Size = 0x00000001e0000000 = 7680 MiB
CPUs found: 2 Max CPUs supported: 2
Comparing RSDP and RSDP
Therefore, allow disabling only k_spec() function in order to allow
fuzzers to examine the remaining part in that file.
[1] https://syzkaller.appspot.com/bug?id=321861b1588b44d064b779b92293c5d55cfe8430
Link: http://lkml.kernel.org/r/20200421131951.4948-2-penguin-kernel@xxxxxxxxxxxxxxxxxxx
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Jiri Slaby <jslaby@xxxxxxxx>
Cc: Matthew Garrett <mjg59@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: "Theodore Y . Ts'o" <tytso@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/tty/vt/keyboard.c | 2 ++
lib/Kconfig.twist | 7 +++++++
2 files changed, 9 insertions(+)
--- a/drivers/tty/vt/keyboard.c~twist-allow-disabling-k_spec-function-in-drivers-tty-vt-keyboardc
+++ a/drivers/tty/vt/keyboard.c
@@ -633,6 +633,8 @@ static void k_spec(struct vc_data *vc, u
kbd->kbdmode == VC_OFF) &&
value != KVAL(K_SAK))
return; /* SAK is allowed even in raw mode */
+ if (IS_ENABLED(CONFIG_TWIST_DISABLE_KBD_K_SPEC_HANDLER))
+ return;
fn_handler[value](vc);
}
--- a/lib/Kconfig.twist~twist-allow-disabling-k_spec-function-in-drivers-tty-vt-keyboardc
+++ a/lib/Kconfig.twist
@@ -10,4 +10,11 @@ menuconfig TWIST_KERNEL_BEHAVIOR
if TWIST_KERNEL_BEHAVIOR
+config TWIST_DISABLE_KBD_K_SPEC_HANDLER
+ bool "Disable k_spec() function in drivers/tty/vt/keyboard.c"
+ help
+ k_spec() function allows triggering e.g. Ctrl-Alt-Del event.
+ Such event is annoying for fuzz testing which wants to test
+ kernel code without rebooting the system.
+
endif # TWIST_KERNEL_BEHAVIOR
_
Patches currently in -mm which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
info-task-hung-in-generic_file_write_iter.patch
info-task-hung-in-generic_file_write-fix.patch
add-kernel-config-option-for-twisting-kernel-behavior.patch
twist-allow-disabling-k_spec-function-in-drivers-tty-vt-keyboardc.patch
twist-add-option-for-selecting-twist-options-for-syzkallers-testing.patch
