linux-kernel - [tip:timers/core] hrtimer: Catch invalid clockids again

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Date:   Sat, 18 Feb 2017 02:01:02 -0800
From:   tip-bot for Marc Zyngier <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     hpa@...or.com, linux-kernel@...r.kernel.org, tglx@...utronix.de,
        marc.zyngier@....com, mingo@...nel.org,
        christoffer.dall@...aro.org, tn@...ihalf.com
Subject: [tip:timers/core] hrtimer: Catch invalid clockids again

Commit-ID:  336a9cde10d641e70bac67d90ae91b3190c3edca
Gitweb:     http://git.kernel.org/tip/336a9cde10d641e70bac67d90ae91b3190c3edca
Author:     Marc Zyngier <marc.zyngier@....com>
AuthorDate: Fri, 15 Jan 2016 17:41:09 +0000
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Sat, 18 Feb 2017 10:58:39 +0100

hrtimer: Catch invalid clockids again

commit 82e88ff1ea94 ("hrtimer: Revert CLOCK_MONOTONIC_RAW support") removed
unfortunately a sanity check in the hrtimer code which was part of that
MONOTONIC_RAW patch series.

It would have caught the bogus usage of CLOCK_MONOTONIC_RAW in the wireless
code. So bring it back.

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.
    
Detect invalid clockids, map them to CLOCK_MONOTONIC and emit a warning.

[ tglx: Replaced the BUG by a WARN and gracefully map to CLOCK_MONOTONIC ]

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
Cc: Tomasz Nowicki <tn@...ihalf.com>
Cc: Christoffer Dall <christoffer.dall@...aro.org>
Link: http://lkml.kernel.org/r/1452879670-16133-3-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/time/hrtimer.c | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index edabde6..8e11d8d 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -94,17 +94,15 @@ 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_BOOTTIME]	= HRTIMER_BASE_BOOTTIME,
 	[CLOCK_TAI]		= HRTIMER_BASE_TAI,
 };
 
-static inline int hrtimer_clockid_to_base(clockid_t clock_id)
-{
-	return hrtimer_clock_to_base_table[clock_id];
-}
-
 /*
  * Functions and macros which are different for UP/SMP systems are kept in a
  * single place
@@ -1081,6 +1079,18 @@ u64 hrtimer_get_next_event(void)
 }
 #endif
 
+static inline int hrtimer_clockid_to_base(clockid_t clock_id)
+{
+	if (likely(clock_id < MAX_CLOCKS)) {
+		int base = hrtimer_clock_to_base_table[clock_id];
+
+		if (likely(base != HRTIMER_MAX_CLOCK_BASES))
+			return base;
+	}
+	WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
+	return HRTIMER_BASE_MONOTONIC;
+}
+
 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 			   enum hrtimer_mode mode)
 {