user/sven/linux.git/kernel/printk, branch v4.4.151

braille-console: Fix value returned by _braille_console_setup

2018-03-22T08:23:23Z

[ Upstream commit 2ed2b8621be2708c0f6d61fe9841e9ad8b9753f0 ] commit bbeddf52adc1 ("printk: move braille console support into separate braille.[ch] files") introduced _braille_console_setup() to outline the braille initialization code. There was however some confusion over the value it was supposed to return. commit 2cfe6c4ac7ee ("printk: Fix return of braille_register_console()") tried to fix it but failed to. This fixes and documents the returned value according to the use in printk.c: non-zero return means a parsing error, and thus this console configuration should be ignored. Signed-off-by: Samuel Thibault Cc: Aleksey Makarov Cc: Joe Perches Cc: Ming Lei Cc: Steven Rostedt Acked-by: Petr Mladek Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

printk: use rcuidle console tracepoint

2017-02-23T16:43:10Z

commit fc98c3c8c9dcafd67adcce69e6ce3191d5306c9c upstream. Use rcuidle console tracepoint because, apparently, it may be issued from an idle CPU: hw-breakpoint: Failed to enable monitor mode on CPU 0. hw-breakpoint: CPU 0 failed to disable vector catch =============================== [ ERR: suspicious RCU usage. ] 4.10.0-rc8-next-20170215+ #119 Not tainted ------------------------------- ./include/trace/events/printk.h:32 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from idle CPU! rcu_scheduler_active = 2, debug_locks = 0 RCU used illegally from extended quiescent state! 2 locks held by swapper/0/0: #0: (cpu_pm_notifier_lock){......}, at: [] cpu_pm_exit+0x10/0x54 #1: (console_lock){+.+.+.}, at: [] vprintk_emit+0x264/0x474 stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.10.0-rc8-next-20170215+ #119 Hardware name: Generic OMAP4 (Flattened Device Tree) console_unlock vprintk_emit vprintk_default printk reset_ctrl_regs dbg_cpu_pm_notify notifier_call_chain cpu_pm_exit omap_enter_idle_coupled cpuidle_enter_state cpuidle_enter_state_coupled do_idle cpu_startup_entry start_kernel This RCU warning, however, is suppressed by lockdep_off() in printk(). lockdep_off() increments the ->lockdep_recursion counter and thus disables RCU_LOCKDEP_WARN() and debug_lockdep_rcu_enabled(), which want lockdep to be enabled "current->lockdep_recursion == 0". Link: http://lkml.kernel.org/r/20170217015932.11898-1-sergey.senozhatsky@gmail.com Signed-off-by: Sergey Senozhatsky Reported-by: Tony Lindgren Tested-by: Tony Lindgren Acked-by: Paul E. McKenney Acked-by: Steven Rostedt (VMware) Cc: Petr Mladek Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Tony Lindgren Cc: Russell King Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

printk: fix parsing of "brl=" option

2016-10-07T13:23:43Z

commit ae6c33ba6e37eea3012fe2640b22400ef3f2d0f3 upstream. Commit bbeddf52adc1 ("printk: move braille console support into separate braille.[ch] files") moved the parsing of braille-related options into _braille_console_setup(), changing the type of variable str from char* to char**. In this commit, memcmp(str, "brl,", 4) was correctly updated to memcmp(*str, "brl,", 4) but not memcmp(str, "brl=", 4). Update the code to make "brl=" option work again and replace memcmp() with strncmp() to make the compiler able to detect such an issue. Fixes: bbeddf52adc1 ("printk: move braille console support into separate braille.[ch] files") Link: http://lkml.kernel.org/r/20160823165700.28952-1-nicolas.iooss_linux@m4x.org Signed-off-by: Nicolas Iooss Cc: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

printk: do cond_resched() between lines while outputting to consoles

2016-02-17T20:30:57Z

commit 8d91f8b15361dfb438ab6eb3b319e2ded43458ff upstream. @console_may_schedule tracks whether console_sem was acquired through lock or trylock. If the former, we're inside a sleepable context and console_conditional_schedule() performs cond_resched(). This allows console drivers which use console_lock for synchronization to yield while performing time-consuming operations such as scrolling. However, the actual console outputting is performed while holding irq-safe logbuf_lock, so console_unlock() clears @console_may_schedule before starting outputting lines. Also, only a few drivers call console_conditional_schedule() to begin with. This means that when a lot of lines need to be output by console_unlock(), for example on a console registration, the task doing console_unlock() may not yield for a long time on a non-preemptible kernel. If this happens with a slow console devices, for example a serial console, the outputting task may occupy the cpu for a very long time. Long enough to trigger softlockup and/or RCU stall warnings, which in turn pile more messages, sometimes enough to trigger the next cycle of warnings incapacitating the system. Fix it by making console_unlock() insert cond_resched() between lines if @console_may_schedule. Signed-off-by: Tejun Heo Reported-by: Calvin Owens Acked-by: Jan Kara Cc: Dave Jones Cc: Kyle McMartin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

printk: prevent userland from spoofing kernel messages

2015-11-07T01:50:42Z

The following statement of ABI/testing/dev-kmsg is not quite right: It is not possible to inject messages from userspace with the facility number LOG_KERN (0), to make sure that the origin of the messages can always be reliably determined. Userland actually can inject messages with a facility of 0 by abusing the fact that the facility is stored in a u8 data type. By using a facility which is a multiple of 256 the assignment of msg->facility in log_store() implicitly truncates it to 0, i.e. LOG_KERN, allowing users of /dev/kmsg to spoof kernel messages as shown below: The following call... # printf '<%d>Kernel panic - not syncing: beer empty\n' 0 >/dev/kmsg ...leads to the following log entry (dmesg -x | tail -n 1): user :emerg : [ 66.137758] Kernel panic - not syncing: beer empty However, this call... # printf '<%d>Kernel panic - not syncing: beer empty\n' 0x800 >/dev/kmsg ...leads to the slightly different log entry (note the kernel facility): kern :emerg : [ 74.177343] Kernel panic - not syncing: beer empty Fix that by limiting the user provided facility to 8 bit right from the beginning and catch the truncation early. Fixes: 7ff9554bb578 ("printk: convert byte-buffer to variable-length...") Signed-off-by: Mathias Krause Cc: Greg Kroah-Hartman Cc: Petr Mladek Cc: Alex Elder Cc: Joe Perches Cc: Kay Sievers Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

pstore: add pstore unregister

2015-10-22T15:59:18Z

pstore doesn't support unregistering yet. It was marked as TODO. This patch adds some code to fix it: 1) Add functions to unregister kmsg/console/ftrace/pmsg. 2) Add a function to free compression buffer. 3) Unmap the memory and free it. 4) Add a function to unregister pstore filesystem. Signed-off-by: Geliang Tang Acked-by: Kees Cook [Removed __exit annotation from ramoops_remove(). Reported by Arnd Bergmann] Signed-off-by: Tony Luck

kexec: split kexec_load syscall from kexec core code

2015-09-10T20:29:01Z

There are two kexec load syscalls, kexec_load another and kexec_file_load. kexec_file_load has been splited as kernel/kexec_file.c. In this patch I split kexec_load syscall code to kernel/kexec.c. And add a new kconfig option KEXEC_CORE, so we can disable kexec_load and use kexec_file_load only, or vice verse. The original requirement is from Ted Ts'o, he want kexec kernel signature being checked with CONFIG_KEXEC_VERIFY_SIG enabled. But kexec-tools use kexec_load syscall can bypass the checking. Vivek Goyal proposed to create a common kconfig option so user can compile in only one syscall for loading kexec kernel. KEXEC/KEXEC_FILE selects KEXEC_CORE so that old config files still work. Because there's general code need CONFIG_KEXEC_CORE, so I updated all the architecture Kconfig with a new option KEXEC_CORE, and let KEXEC selects KEXEC_CORE in arch Kconfig. Also updated general kernel code with to kexec_load syscall. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Dave Young Cc: Eric W. Biederman Cc: Vivek Goyal Cc: Petr Tesarik Cc: Theodore Ts'o Cc: Josh Boyer Cc: David Howells Cc: Geert Uytterhoeven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

printk: improve the description of /dev/kmsg line format

2015-07-01T02:44:59Z

The comment about /dev/kmsg does not mention the additional values which may actually be exported, fix that. Also move up the part of the comment instructing the users to ignore these additional values, this way the reading is more fluent and logically compact. Signed-off-by: Antonio Ospite Cc: Joe Perches Cc: Jonathan Corbet Cc: Tejun Heo Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

check_syslog_permissions() cleanup

2015-06-26T00:00:39Z

Patch fixes drawbacks in heck_syslog_permissions() noticed by AKPM: "from_file handling makes me cry. That's not a boolean - it's an enumerated value with two values currently defined. But the code in check_syslog_permissions() treats it as a boolean and also hardwires the knowledge that SYSLOG_FROM_PROC == 1 (or == `true`). And the name is wrong: it should be called from_proc to match SYSLOG_FROM_PROC." Signed-off-by: Vasily Averin Cc: Kees Cook Cc: Josh Boyer Cc: Eric Paris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

security_syslog() should be called once only

2015-06-26T00:00:39Z

The final version of commit 637241a900cb ("kmsg: honor dmesg_restrict sysctl on /dev/kmsg") lost few hooks, as result security_syslog() are processed incorrectly: - open of /dev/kmsg checks syslog access permissions by using check_syslog_permissions() where security_syslog() is not called if dmesg_restrict is set. - syslog syscall and /proc/kmsg calls do_syslog() where security_syslog can be executed twice (inside check_syslog_permissions() and then directly in do_syslog()) With this patch security_syslog() is called once only in all syslog-related operations regardless of dmesg_restrict value. Fixes: 637241a900cb ("kmsg: honor dmesg_restrict sysctl on /dev/kmsg") Signed-off-by: Vasily Averin Cc: Kees Cook Cc: Josh Boyer Cc: Eric Paris Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds