From: Thomas Gleixner <tglx@linutronix.de> To: LKML <linux-kernel@vger.kernel.org> Cc: Ingo Molnar <mingo@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, David Woodhouse <dwmw@amazon.co.uk>, Dan Williams <dan.j.williams@intel.com>, Greg KH <gregkh@linuxfoundation.org> Subject: [PATCH] posix-timers: Protect posix clock array access against speculation Date: Thu, 15 Feb 2018 14:27:30 +0100 (CET) Message-ID: <alpine.DEB.2.21.1802151424490.1296@nanos.tec.linutronix.de> (raw) 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))]; }
next reply index Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-02-15 13:27 Thomas Gleixner [this message] 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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