4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Peter Zijlstra <pet...@infradead.org>
commit 354d7793070611b4df5a79fbb0f12752d0ed0cc5 upstream.
> kernel/sched/autogroup.c:230 proc_sched_autogroup_set_nice() warn: potential
> spectre issue 'sched_prio_to_weight'
Userspace controls @nice, sanitize the array index.
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: <sta...@kernel.org>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
kernel/sched/autogroup.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
--- a/kernel/sched/autogroup.c
+++ b/kernel/sched/autogroup.c
@@ -4,6 +4,7 @@
#include <linux/utsname.h>
#include <linux/security.h>
#include <linux/export.h>
+#include <linux/nospec.h>
#include "sched.h"
@@ -212,7 +213,7 @@ int proc_sched_autogroup_set_nice(struct
static unsigned long next = INITIAL_JIFFIES;
struct autogroup *ag;
unsigned long shares;
- int err;
+ int err, idx;
if (nice < MIN_NICE || nice > MAX_NICE)
return -EINVAL;
@@ -230,7 +231,9 @@ int proc_sched_autogroup_set_nice(struct
next = HZ / 10 + jiffies;
ag = autogroup_task_get(p);
- shares = scale_load(sched_prio_to_weight[nice + 20]);
+
+ idx = array_index_nospec(nice + 20, 40);
+ shares = scale_load(sched_prio_to_weight[idx]);
down_write(&ag->lock);
err = sched_group_set_shares(ag->tg, shares);
