Commit-ID: 7281c8dec8a87685cb54d503d8cceef5a0fc2fdd
Gitweb: https://git.kernel.org/tip/7281c8dec8a87685cb54d503d8cceef5a0fc2fdd
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Fri, 20 Apr 2018 14:29:51 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Sat, 5 May 2018 08:32:36 +0200
sched/core: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]
> 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@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
kernel/sched/core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ffde9eebc846..092f7c4de903 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -8,6 +8,7 @@
#include "sched.h"
#include <linux/kthread.h>
+#include <linux/nospec.h>
#include <asm/switch_to.h>
#include <asm/tlb.h>
@@ -6923,11 +6924,15 @@ static int cpu_weight_nice_write_s64(struct cgroup_subsys_state *css,
struct cftype *cft, s64 nice)
{
unsigned long weight;
+ int idx;
if (nice < MIN_NICE || nice > MAX_NICE)
return -ERANGE;
- weight = sched_prio_to_weight[NICE_TO_PRIO(nice) - MAX_RT_PRIO];
+ idx = NICE_TO_PRIO(nice) - MAX_RT_PRIO;
+ idx = array_index_nospec(idx, 40);
+ weight = sched_prio_to_weight[idx];
+
return sched_group_set_shares(css_tg(css), scale_load(weight));
}
#endif
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