linux-kernel - [PATCH 3.16 261/366] sched/core: Fix possible Spectre-v1 indexing for sched_prio_to

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <lsq.1539530741.411176669@decadent.org.uk>
Date:   Sun, 14 Oct 2018 16:25:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Mike Galbraith" <efault@....de>,
        "Ingo Molnar" <mingo@...nel.org>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Dan Carpenter" <dan.carpenter@...cle.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Peter Zijlstra" <peterz@...radead.org>
Subject: [PATCH 3.16 261/366] sched/core: Fix possible Spectre-v1 indexing
 for sched_prio_to_weight[]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Zijlstra <peterz@...radead.org>

commit 7281c8dec8a87685cb54d503d8cceef5a0fc2fdd upstream.

> kernel/sched/core.c:6921 cpu_weight_nice_write_s64() warn: potential spectre issue 'sched_prio_to_weight'

Userspace controls @nice, so sanitize the value before using it to
index an array.

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
[bwh: Backported to 3.16: Vulnerable array lookup is in set_load_weight()]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -74,6 +74,7 @@
 #include <linux/binfmts.h>
 #include <linux/context_tracking.h>
 #include <linux/compiler.h>
+#include <linux/nospec.h>
 
 #include <asm/switch_to.h>
 #include <asm/tlb.h>
@@ -820,6 +821,8 @@ static void set_load_weight(struct task_
 		return;
 	}
 
+	prio = array_index_nospec(prio, 40);
+
 	load->weight = scale_load(prio_to_weight[prio]);
 	load->inv_weight = prio_to_wmult[prio];
 }