linux-stable/kernel
Petr Mladek 4a998e322a printk/NMI: fix up handling of the full nmi log buffer
vsnprintf() adds the trailing '\0' but it does not count it into the
number of printed characters.  The result is that there is one byte less
space for the real characters in the buffer.

The broken check for the free space might cause that we will repeatedly
try to print 1 character into the buffer, never reach the full buffer,
and do not count the messages as missed.

Also vsnprintf() returns the number of characters that would be printed
if the buffer was big enough.  As a result, s->len might be bigger than
the size of the buffer[*].  And the printk() function might return
bigger len than it really printed.  Both problems are fixed by using
vscnprintf() instead.

Note that I though about increasing the number of missed messages even
when the message was shrunken.  But it made the code even more
complicated.  I think that it is not worth it.  Shrunken messages are
usually easy to recognize.  And it should be a corner case.

[*] The overflown s->len value is crazy and unexpected.  I "made a
mistake" and reported this situation as an internal error when fixed
handling of PR_CONT headers in some other patch.

Link: http://lkml.kernel.org/r/20161208174912.GA17042@linux.suse
Signed-off-by: Petr Mladek <pmladek@suse.com>
CcL Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Takashi Iwai <tiwai@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-12-12 18:55:09 -08:00
..
bpf bpf: xdp: Allow head adjustment in XDP prog 2016-12-08 14:25:13 -05:00
configs config: android: enable CONFIG_SECCOMP 2016-10-11 15:06:32 -07:00
debug
events Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-12-10 16:21:55 -05:00
gcov gcov: add support for gcc version >= 6 2016-07-15 14:54:27 +09:00
irq genirq: Use irq type from irqdata instead of irqdesc 2016-11-08 15:15:19 +01:00
livepatch livepatch/module: make TAINT_LIVEPATCH module-specific 2016-08-26 14:42:08 +02:00
locking Merge branch 'linus' into locking/core, to pick up fixes 2016-12-11 13:07:13 +01:00
power PM / sleep: fix device reference leak in test_suspend 2016-11-02 05:10:04 +01:00
printk printk/NMI: fix up handling of the full nmi log buffer 2016-12-12 18:55:09 -08:00
rcu rcu: Don't kick unless grace period or request 2016-11-14 10:46:31 -08:00
sched Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-12 12:15:10 -08:00
time Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-12 12:15:10 -08:00
trace Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-22 13:27:16 -05:00
.gitignore
acct.c
async.c
audit.c audit: remove useless synchronize_net() 2016-12-01 11:29:02 -05:00
audit.h Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit 2016-07-29 17:54:17 -07:00
audit_fsnotify.c
audit_tree.c audit: cleanup prune_tree_thread 2016-04-04 09:46:47 -04:00
audit_watch.c Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit 2016-09-01 15:55:56 -07:00
auditfilter.c audit: add fields to exclude filter by reusing user filter 2016-06-27 11:01:00 -04:00
auditsc.c Merge branch 'stable-4.9' of git://git.infradead.org/users/pcmoore/audit 2016-10-04 14:21:41 -07:00
backtracetest.c
bounds.c
capability.c kernel: Add noaudit variant of ns_capable() 2016-06-06 20:16:18 +10:00
cgroup.c cgroup: add support for eBPF programs 2016-11-25 16:25:52 -05:00
cgroup_freezer.c
cgroup_pids.c cgroup: Use lld instead of ld when printing pids controller events_limit 2016-06-21 15:03:36 -04:00
compat.c
configs.c
context_tracking.c
cpu.c hotplug: Make register and unregister notifier API symmetric 2016-12-08 10:08:41 +01:00
cpu_pm.c
cpuset.c Merge branch 'for-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2016-10-14 12:18:50 -07:00
crash_dump.c
cred.c cred: Reject inodes with invalid ids in set_create_file_as() 2016-06-30 18:05:09 -05:00
delayacct.c
dma.c
elfcore.c
exec_domain.c
exit.c sched/autogroup: Do not use autogroup->tg in zombie threads 2016-11-22 12:33:43 +01:00
extable.c
fork.c kernel/fork: use vfree_atomic() to free thread stack 2016-12-12 18:55:08 -08:00
freezer.c freezer, oom: check TIF_MEMDIE on the correct task 2016-07-28 16:07:41 -07:00
futex.c sched/wake_q: Rename WAKE_Q to DEFINE_WAKE_Q 2016-11-21 10:29:01 +01:00
futex_compat.c
groups.c cred: simpler, 1D supplementary groups 2016-10-07 18:46:30 -07:00
hung_task.c hung_task: decrement sysctl_hung_task_warnings only if it is positive 2016-12-12 18:55:09 -08:00
irq_work.c
jump_label.c powerpc updates for 4.8 #2 2016-08-05 09:00:54 -04:00
kallsyms.c kallsyms: add support for relative offsets in kallsyms address table 2016-03-15 16:55:16 -07:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/mutex: Allow MUTEX_SPIN_ON_OWNER when DEBUG_MUTEXES 2016-10-25 11:31:51 +02:00
Kconfig.preempt
kcov.c kcov: add missing #include <linux/sched.h> 2016-12-07 17:10:00 -08:00
kexec.c kexec: allow architectures to override boot mapping 2016-08-02 19:35:27 -04:00
kexec_core.c kexec: add restriction on kexec_load() segment sizes 2016-08-02 19:35:31 -04:00
kexec_file.c kexec: fix double-free when failing to relocate the purgatory 2016-09-01 17:52:01 -07:00
kexec_internal.h
kmod.c
kprobes.c kprobes: include <asm/sections.h> instead of <asm-generic/sections.h> 2016-10-11 15:06:31 -07:00
ksysfs.c kexec: add a kexec_crash_loaded() function 2016-08-02 19:35:30 -04:00
kthread.c kthread: add __printf attributes 2016-12-12 18:55:06 -08:00
latencytop.c
Makefile userns: Add per user namespace sysctls. 2016-08-08 13:18:58 -05:00
membarrier.c
memremap.c mm: fix cache mode of dax pmd mappings 2016-09-09 17:34:46 -07:00
module-internal.h
module.c Re-enable CONFIG_MODVERSIONS in a slightly weaker form 2016-11-29 16:01:30 -08:00
module_signing.c KEYS: Move the point of trust determination to __key_link() 2016-04-11 22:43:43 +01:00
notifier.c
nsproxy.c
padata.c padata: Convert to hotplug state machine 2016-09-19 21:44:30 +02:00
panic.c x86/panic: replace smp_send_stop() with kdump friendly version in panic path 2016-10-11 15:06:32 -07:00
params.c
pid.c remove lots of IS_ERR_VALUE abuses 2016-05-27 15:26:11 -07:00
pid_namespace.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
profile.c profile: Convert to hotplug state machine 2016-07-15 10:41:42 +02:00
ptrace.c mm: replace access_process_vm() write parameter with gup_flags 2016-10-19 08:31:25 -07:00
range.c
reboot.c
relay.c relay: Use irq_work instead of plain timer for deferred wakeup 2016-10-11 15:06:32 -07:00
resource.c /proc/iomem: only expose physical resource addresses to privileged users 2016-04-14 12:56:09 -07:00
seccomp.c bpf: drop unnecessary context cast from BPF_PROG_RUN 2016-11-27 20:38:47 -05:00
signal.c x86/signal: Add SA_{X32,IA32}_ABI sa_flags 2016-09-14 21:28:11 +02:00
smp.c kernel/smp: Tell the user we're bringing up secondary CPUs 2016-10-26 12:02:35 +02:00
smpboot.c kthread/smpboot: do not park in kthread_create_on_cpu() 2016-10-11 15:06:33 -07:00
smpboot.h
softirq.c softirq: Display IRQ_POLL for irq-poll statistics 2016-10-21 15:45:47 -06:00
stacktrace.c
stop_machine.c locking/core, stop_machine: Yield the CPU during stop machine() 2016-11-16 10:15:09 +01:00
sys.c prctl: remove one-shot limitation for changing exe link 2016-12-12 18:55:06 -08:00
sys_ni.c x86/pkeys: Fix pkeys build breakage for some non-x86 arches 2016-09-13 14:41:36 +02:00
sysctl.c sched/fair: Kill the unused 'sched_shares_window_ns' tunable 2016-10-20 08:44:57 +02:00
sysctl_binary.c kernel/sysctl_binary.c: use generic UUID library 2016-05-20 17:58:30 -07:00
task_work.c task_work: use READ_ONCE/lockless_dereference, avoid pi_lock if !task_works 2016-08-02 19:35:02 -04:00
taskstats.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-15 10:54:36 -05:00
test_kprobes.c
torture.c torture: Convert torture_shutdown() to hrtimer 2016-08-22 10:01:49 -07:00
tracepoint.c kernel/...: convert pr_warning to pr_warn 2016-03-22 15:36:02 -07:00
tsacct.c
ucount.c mntns: Add a limit on the number of mount namespaces. 2016-08-31 07:28:35 -05:00
uid16.c cred: simpler, 1D supplementary groups 2016-10-07 18:46:30 -07:00
up.c smp: Add function to execute a function synchronously on a CPU 2016-09-05 13:52:39 +02:00
user-return-notifier.c
user.c
user_namespace.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
utsname.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
utsname_sysctl.c
watchdog.c Revert "perf/x86/intel, watchdog: Switch NMI watchdog to ref cycles on x86" 2016-07-10 20:58:36 +02:00
workqueue.c kthread: rename probe_kthread_data() to kthread_probe_data() 2016-10-11 15:06:33 -07:00
workqueue_internal.h