On Thu, Feb 4, 2016 at 3:04 PM, Andy Shevchenko
[off-list ref] wrote:

On Thu, Feb 4, 2016 at 11:00 PM, Kees Cook [off-list ref] wrote:

quoted

This changes several users of manual "on"/"off" parsing to use strtobool.
(Which means they will now parse y/n/1/0 meaningfully too.)

I like this change, but can you carefully check the acceptance of the
returned value?
Briefly I saw 1 or 0 as okay in different places.

Maybe I missed something, but I think this is actually a bug fix. The
two cases are early_param and __setup:

For early_param, the functions are called when walking the command
line in do_early_param via parse_args in parse_early_options. Any
non-zero return values produce a warning (in do_early_param not
parse_args). So this is a bug fix, since the function I touched would
(almost) always return 0, even with bad values (i.e. fixes unreported
bad arguments):

early_param early_parse_stp always 0
early_param early_parse_topology always 0
early_param parse_gart_mem always 0 unless !p (then -EINVAL)

For __setup, these are handled by obsolete_checksetup via
unknown_bootoption via parse_args in start_kernel, as a way to merge
__setup calls that should really be in param (i.e. non-early __setup).
Return values are bubbled up into parse_args and hit:

                default:
                        pr_err("%s: `%s' invalid for parameter `%s'\n",
                               doing, val ?: "", param);
                        break;

So this is also a bug fix, since these __setup functions returned inverted
values or always failed:

__setup rtasmsgs_setup always 1
__setup setup_cede_offline 1 on success, otherwise 0
__setup setup_hrtimer_hres 1 on success, otherwise 0
__setup setup_tick_nohz 1 on success, otherwise 0

So if you specified any of these, they would trigger a bogus "invalid
parameter" report.

I will double-check...

-Kees

quoted

Signed-off-by: Kees Cook <redacted>
Acked-by: Heiko Carstens <redacted>
Acked-by: Michael Ellerman <mpe-Gsx/Oe8HsFggBc27wqDAHg@public.gmane.org>
Cc: x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org
Cc: linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Cc: linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
---
 arch/powerpc/kernel/rtasd.c                  |  9 ++-------
 arch/powerpc/platforms/pseries/hotplug-cpu.c | 10 ++--------
 arch/s390/kernel/time.c                      |  8 ++------
 arch/s390/kernel/topology.c                  |  7 ++-----
 arch/x86/kernel/aperture_64.c                | 12 ++----------
 include/linux/tick.h                         |  2 +-
 kernel/time/hrtimer.c                        | 10 ++--------
 kernel/time/tick-sched.c                     | 10 ++--------
 8 files changed, 15 insertions(+), 53 deletions(-)

diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c
index 5a2c049c1c61..567ed5a2f43a 100644
--- a/arch/powerpc/kernel/rtasd.c
+++ b/arch/powerpc/kernel/rtasd.c

@@ -49,7 +49,7 @@ static unsigned int rtas_error_log_buffer_max;
 static unsigned int event_scan;
 static unsigned int rtas_event_scan_rate;

-static int full_rtas_msgs = 0;
+static bool full_rtas_msgs;

 /* Stop logging to nvram after first fatal error */
 static int logging_enabled; /* Until we initialize everything,

@@ -592,11 +592,6 @@ __setup("surveillance=", surveillance_setup);

 static int __init rtasmsgs_setup(char *str)
 {
-       if (strcmp(str, "on") == 0)
-               full_rtas_msgs = 1;
-       else if (strcmp(str, "off") == 0)
-               full_rtas_msgs = 0;
-
-       return 1;
+       return kstrtobool(str, 0, &full_rtas_msgs);
 }
 __setup("rtasmsgs=", rtasmsgs_setup);

diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
index 32274f72fe3f..b9787cae4108 100644
--- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
+++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c

@@ -47,20 +47,14 @@ static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE;

 static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE;

-static int cede_offline_enabled __read_mostly = 1;
+static bool cede_offline_enabled __read_mostly = true;

 /*
  * Enable/disable cede_offline when available.
  */
 static int __init setup_cede_offline(char *str)
 {
-       if (!strcmp(str, "off"))
-               cede_offline_enabled = 0;
-       else if (!strcmp(str, "on"))
-               cede_offline_enabled = 1;
-       else
-               return 0;
-       return 1;
+       return kstrtobool(str, 0, &cede_offline_enabled);
 }

 __setup("cede_offline=", setup_cede_offline);

diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 99f84ac31307..dff6ce1b84b2 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c

@@ -1433,7 +1433,7 @@ device_initcall(etr_init_sysfs);
 /*
  * Server Time Protocol (STP) code.
  */
-static int stp_online;
+static bool stp_online;
 static struct stp_sstpi stp_info;
 static void *stp_page;

@@ -1444,11 +1444,7 @@ static struct timer_list stp_timer;

 static int __init early_parse_stp(char *p)
 {
-       if (strncmp(p, "off", 3) == 0)
-               stp_online = 0;
-       else if (strncmp(p, "on", 2) == 0)
-               stp_online = 1;
-       return 0;
+       return kstrtobool(p, 0, &stp_online);
 }
 early_param("stp", early_parse_stp);

diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
index 40b8102fdadb..5d8a80651f61 100644
--- a/arch/s390/kernel/topology.c
+++ b/arch/s390/kernel/topology.c

@@ -37,7 +37,7 @@ static void set_topology_timer(void);
 static void topology_work_fn(struct work_struct *work);
 static struct sysinfo_15_1_x *tl_info;

-static int topology_enabled = 1;
+static bool topology_enabled = true;
 static DECLARE_WORK(topology_work, topology_work_fn);

 /*

@@ -444,10 +444,7 @@ static const struct cpumask *cpu_book_mask(int cpu)

 static int __init early_parse_topology(char *p)
 {
-       if (strncmp(p, "off", 3))
-               return 0;
-       topology_enabled = 0;
-       return 0;
+       return kstrtobool(p, 0, &topology_enabled);
 }
 early_param("topology", early_parse_topology);

diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
index 6e85f713641d..6b423754083a 100644
--- a/arch/x86/kernel/aperture_64.c
+++ b/arch/x86/kernel/aperture_64.c

@@ -227,19 +227,11 @@ static u32 __init search_agp_bridge(u32 *order, int *valid_agp)
        return 0;
 }

-static int gart_fix_e820 __initdata = 1;
+static bool gart_fix_e820 __initdata = true;

 static int __init parse_gart_mem(char *p)
 {
-       if (!p)
-               return -EINVAL;
-
-       if (!strncmp(p, "off", 3))
-               gart_fix_e820 = 0;
-       else if (!strncmp(p, "on", 2))
-               gart_fix_e820 = 1;
-
-       return 0;
+       return kstrtobool(p, 0, &gart_fix_e820);
 }
 early_param("gart_fix_e820", parse_gart_mem);

diff --git a/include/linux/tick.h b/include/linux/tick.h
index 97fd4e543846..0ecdf0e248f4 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h

@@ -98,7 +98,7 @@ static inline void tick_broadcast_exit(void)
 }

 #ifdef CONFIG_NO_HZ_COMMON
-extern int tick_nohz_enabled;
+extern bool tick_nohz_enabled;
 extern int tick_nohz_tick_stopped(void);
 extern void tick_nohz_idle_enter(void);
 extern void tick_nohz_idle_exit(void);

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 435b8850dd80..456f066148d5 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c

@@ -515,7 +515,7 @@ static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
 /*
  * High resolution timer enabled ?
  */
-static int hrtimer_hres_enabled __read_mostly  = 1;
+static bool hrtimer_hres_enabled __read_mostly  = true;
 unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
 EXPORT_SYMBOL_GPL(hrtimer_resolution);

@@ -524,13 +524,7 @@ EXPORT_SYMBOL_GPL(hrtimer_resolution);
  */
 static int __init setup_hrtimer_hres(char *str)
 {
-       if (!strcmp(str, "off"))
-               hrtimer_hres_enabled = 0;
-       else if (!strcmp(str, "on"))
-               hrtimer_hres_enabled = 1;
-       else
-               return 0;
-       return 1;
+       return kstrtobool(str, 0, &hrtimer_hres_enabled);
 }

 __setup("highres=", setup_hrtimer_hres);

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 9d7a053545f5..b57f822c2069 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c

@@ -387,20 +387,14 @@ void __init tick_nohz_init(void)
 /*
  * NO HZ enabled ?
  */
-int tick_nohz_enabled __read_mostly = 1;
+bool tick_nohz_enabled __read_mostly  = true;
 unsigned long tick_nohz_active  __read_mostly;
 /*
  * Enable / Disable tickless mode
  */
 static int __init setup_tick_nohz(char *str)
 {
-       if (!strcmp(str, "off"))
-               tick_nohz_enabled = 0;
-       else if (!strcmp(str, "on"))
-               tick_nohz_enabled = 1;
-       else
-               return 0;
-       return 1;
+       return kstrtobool(str, 0, &tick_nohz_enabled);
 }

 __setup("nohz=", setup_tick_nohz);
--

2.6.3

--
With Best Regards,
Andy Shevchenko

-- 
Kees Cook
Chrome OS & Brillo Security