[PATCH 4.16 65/72] sched/core: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]

[Greg Kroah-Hartman]

4.16-stable review patch.  If anyone has any objections, please let me know.

--

From: Peter Zijlstra 

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 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman 

---
 kernel/sched/core.c |7 ++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -23,6 +23,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -6873,11 +6874,15 @@ static int cpu_weight_nice_write_s64(str
 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

[PATCH 4.16 65/72] sched/core: Fix possible Spectre-v1 indexing for sched_prio_to_weight[]

[Greg Kroah-Hartman]

4.16-stable review patch.  If anyone has any objections, please let me know.

--

From: Peter Zijlstra 

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 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman 

---
 kernel/sched/core.c |7 ++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -23,6 +23,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 #include 
 #include 
@@ -6873,11 +6874,15 @@ static int cpu_weight_nice_write_s64(str
 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