hrtimer: Catch illegal clockids

It is way too easy to take any random clockid and feed it to
the hrtimer subsystem. At best, it gets mapped to a monotonic
base, but it would be better to just catch illegal values as
early as possible.

This patch does exactly that, mapping illegal clockids to an
illegal base index, and panicing when we detect the illegal
condition.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Tomasz Nowicki <tn@semihalf.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Link: http://lkml.kernel.org/r/1452879670-16133-3-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index a125f222fee2de06c3a5934ad6c956acda8e2e5b..cb0fe70f3c510ffef51c1a3fd320c5da3a1116ea 100644 (file)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -99,6 +99,9 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
 };
 
 static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
+       /* Make sure we catch unsupported clockids */
+       [0 ... MAX_CLOCKS - 1]  = HRTIMER_MAX_CLOCK_BASES,
+
        [CLOCK_REALTIME]        = HRTIMER_BASE_REALTIME,
        [CLOCK_MONOTONIC]       = HRTIMER_BASE_MONOTONIC,
        [CLOCK_MONOTONIC_RAW]   = HRTIMER_BASE_MONOTONIC_RAW,
@@ -108,7 +111,9 @@ static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
 
 static inline int hrtimer_clockid_to_base(clockid_t clock_id)
 {
-       return hrtimer_clock_to_base_table[clock_id];
+       int base = hrtimer_clock_to_base_table[clock_id];
+       BUG_ON(base == HRTIMER_MAX_CLOCK_BASES);
+       return base;
 }
 
 /*