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Commit bb0b090d authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Greg Kroah-Hartman
Browse files

sched/autogroup: Fix possible Spectre-v1 indexing for sched_prio_to_weight[] 



commit 354d7793 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: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f2a42c6b

kernel/sched/autogroup.c

+5 −2
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include <linux/utsname.h>

#include <linux/security.h>

#include <linux/export.h>

#include <linux/nospec.h>



unsigned int __read_mostly sysctl_sched_autogroup_enabled = 1;

static struct autogroup autogroup_default;
@@ -213,7 +214,7 @@ int proc_sched_autogroup_set_nice(struct task_struct *p, int nice) 
	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;
@@ -231,7 +232,9 @@ int proc_sched_autogroup_set_nice(struct task_struct *p, int nice) 


	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);