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* [PATCH] posix-timers: Protect posix clock array access against speculation
@ 2018-02-15 13:27 Thomas Gleixner
  2018-02-15 14:05 ` Rasmus Villemoes
  0 siblings, 1 reply; 13+ messages in thread
From: Thomas Gleixner @ 2018-02-15 13:27 UTC (permalink / raw)
  To: LKML; +Cc: Ingo Molnar, Linus Torvalds, David Woodhouse, Dan Williams, Greg KH

The (clock) id argument of clockid_to_kclock() comes straight from user
space via various syscalls and is used as index into the posix_clocks
array.

Protect it against spectre v1 array out of bounds speculation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
---
 kernel/time/posix-timers.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/kernel/time/posix-timers.c
+++ b/kernel/time/posix-timers.c
@@ -50,6 +50,7 @@
 #include <linux/export.h>
 #include <linux/hashtable.h>
 #include <linux/compat.h>
+#include <linux/nospec.h>
 
 #include "timekeeping.h"
 #include "posix-timers.h"
@@ -1346,11 +1347,14 @@ static const struct k_clock * const posi
 
 static const struct k_clock *clockid_to_kclock(const clockid_t id)
 {
+	clockid_t idx = id;
+
 	if (id < 0)
 		return (id & CLOCKFD_MASK) == CLOCKFD ?
 			&clock_posix_dynamic : &clock_posix_cpu;
 
 	if (id >= ARRAY_SIZE(posix_clocks) || !posix_clocks[id])
 		return NULL;
-	return posix_clocks[id];
+
+	return posix_clocks[array_index_nospec(idx, ARRAY_SIZE(posix_clocks))];
 }

^ permalink raw reply	[flat|nested] 13+ messages in thread

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Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-02-15 13:27 [PATCH] posix-timers: Protect posix clock array access against speculation Thomas Gleixner
2018-02-15 14:05 ` Rasmus Villemoes
2018-02-15 14:39   ` Dan Williams
2018-02-15 14:53     ` Thomas Gleixner
2018-02-15 16:21       ` [PATCH V2] " Thomas Gleixner
2018-02-15 17:01         ` Peter Zijlstra
2018-03-07 18:13           ` Dan Williams
2018-03-22 11:34         ` [tip:timers/urgent] " tip-bot for Thomas Gleixner
2018-02-15 19:52     ` [PATCH] linux/nospec.h: allow index argument to have const-qualified type Rasmus Villemoes
2018-02-15 20:59       ` Linus Torvalds
2018-02-15 21:56         ` Dan Williams
2018-02-15 22:03           ` Linus Torvalds
2018-02-15 22:08             ` Dan Williams

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