sched/debug: Limit sd->*_idx range on sysctl

commit 201c373e8e4823700d3160d5c28e1ab18fd1193e upstream.

Various sd->*_idx's are used for refering the rq's load average table
when selecting a cpu to run.  However they can be set to any number
with sysctl knobs so that it can crash the kernel if something bad is
given. Fix it by limiting them into the actual range.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1345104204-8317-1-git-send-email-namhyung@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.2:
 - Adjust filename
 - s/umode_t/mode_t/]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

1 files changed, 22 insertions, 13 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index d08c9f4b9fce..cfcbe1e9544f 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6672,16 +6672,25 @@ static void sd_free_ctl_entry(struct ctl_table **tablep)
 	*tablep = NULL;
 }
 
+static int min_load_idx = 0;
+static int max_load_idx = CPU_LOAD_IDX_MAX;
+
 static void
 set_table_entry(struct ctl_table *entry,
 		const char *procname, void *data, int maxlen,
-		mode_t mode, proc_handler *proc_handler)
+		mode_t mode, proc_handler *proc_handler,
+		bool load_idx)
 {
 	entry->procname = procname;
 	entry->data = data;
 	entry->maxlen = maxlen;
 	entry->mode = mode;
 	entry->proc_handler = proc_handler;
+
+	if (load_idx) {
+		entry->extra1 = &min_load_idx;
+		entry->extra2 = &max_load_idx;
+	}
 }
 
 static struct ctl_table *
@@ -6693,30 +6702,30 @@ sd_alloc_ctl_domain_table(struct sched_domain *sd)
 		return NULL;
 
 	set_table_entry(&table[0], "min_interval", &sd->min_interval,
-		sizeof(long), 0644, proc_doulongvec_minmax);
+		sizeof(long), 0644, proc_doulongvec_minmax, false);
 	set_table_entry(&table[1], "max_interval", &sd->max_interval,
-		sizeof(long), 0644, proc_doulongvec_minmax);
+		sizeof(long), 0644, proc_doulongvec_minmax, false);
 	set_table_entry(&table[2], "busy_idx", &sd->busy_idx,
-		sizeof(int), 0644, proc_dointvec_minmax);
+		sizeof(int), 0644, proc_dointvec_minmax, true);
 	set_table_entry(&table[3], "idle_idx", &sd->idle_idx,
-		sizeof(int), 0644, proc_dointvec_minmax);
+		sizeof(int), 0644, proc_dointvec_minmax, true);
 	set_table_entry(&table[4], "newidle_idx", &sd->newidle_idx,
-		sizeof(int), 0644, proc_dointvec_minmax);
+		sizeof(int), 0644, proc_dointvec_minmax, true);
 	set_table_entry(&table[5], "wake_idx", &sd->wake_idx,
-		sizeof(int), 0644, proc_dointvec_minmax);
+		sizeof(int), 0644, proc_dointvec_minmax, true);
 	set_table_entry(&table[6], "forkexec_idx", &sd->forkexec_idx,
-		sizeof(int), 0644, proc_dointvec_minmax);
+		sizeof(int), 0644, proc_dointvec_minmax, true);
 	set_table_entry(&table[7], "busy_factor", &sd->busy_factor,
-		sizeof(int), 0644, proc_dointvec_minmax);
+		sizeof(int), 0644, proc_dointvec_minmax, false);
 	set_table_entry(&table[8], "imbalance_pct", &sd->imbalance_pct,
-		sizeof(int), 0644, proc_dointvec_minmax);
+		sizeof(int), 0644, proc_dointvec_minmax, false);
 	set_table_entry(&table[9], "cache_nice_tries",
 		&sd->cache_nice_tries,
-		sizeof(int), 0644, proc_dointvec_minmax);
+		sizeof(int), 0644, proc_dointvec_minmax, false);
 	set_table_entry(&table[10], "flags", &sd->flags,
-		sizeof(int), 0644, proc_dointvec_minmax);
+		sizeof(int), 0644, proc_dointvec_minmax, false);
 	set_table_entry(&table[11], "name", sd->name,
-		CORENAME_MAX_SIZE, 0444, proc_dostring);
+		CORENAME_MAX_SIZE, 0444, proc_dostring, false);
 	/* &table[12] is terminator */
 
 	return table;