swsusp: fix sysfs interface

The sysfs files /sys/power/disk and /sys/power/state do not work as
documented, since they allow the user to write only a few initial
characters of the input string to trigger the option (eg.  'echo pl >
/sys/power/disk' activates the platform mode of hibernation).  Fix it.

Special thanks to Peter Moulder <Peter.Moulder@infotech.monash.edu.au> for
pointing out the problem.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 4 insertions, 3 deletions

diff --git a/kernel/power/disk.c b/kernel/power/disk.c
index b5f0543ed84d..f445b9cd60fb 100644
--- a/kernel/power/disk.c
+++ b/kernel/power/disk.c
@@ -416,7 +416,8 @@ static ssize_t disk_store(struct kset *kset, const char *buf, size_t n)
 
         mutex_lock(&pm_mutex);
         for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
-                if (!strncmp(buf, hibernation_modes[i], len)) {
+                if (len == strlen(hibernation_modes[i])
+                    && !strncmp(buf, hibernation_modes[i], len)) {
                         mode = i;
                         break;
                 }
diff --git a/kernel/power/main.c b/kernel/power/main.c
index b98b80ccf437..8812985f3029 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -290,13 +290,13 @@ static ssize_t state_store(struct kset *kset, const char *buf, size_t n)
         len = p ? p - buf : n;
 
         /* First, check if we are requested to hibernate */
-        if (!strncmp(buf, "disk", len)) {
+        if (len == 4 && !strncmp(buf, "disk", len)) {
                 error = hibernate();
                 return error ? error : n;
         }
 
         for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
-                if (*s && !strncmp(buf, *s, len))
+                if (*s && len == strlen(*s) && !strncmp(buf, *s, len))
                         break;
         }
         if (state < PM_SUSPEND_MAX && *s)