This is a note to let you know that I've just added the patch titled
posix-timers: Protect posix clock array access against speculation
to the 4.15-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: posix-timers-protect-posix-clock-array-access-against-speculation.patch and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 19b558db12f9f4e45a22012bae7b4783e62224da Mon Sep 17 00:00:00 2001
From: Thomas Gleixner tglx@linutronix.de Date: Thu, 15 Feb 2018 17:21:55 +0100 Subject: posix-timers: Protect posix clock array access against speculation
From: Thomas Gleixner tglx@linutronix.de
commit 19b558db12f9f4e45a22012bae7b4783e62224da upstream.
The clockid 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. Remove the redundant check for !posix_clock[id] as this is another source for speculation and does not provide any advantage over the return posix_clock[id] path which returns NULL in that case anyway.
Signed-off-by: Thomas Gleixner tglx@linutronix.de Acked-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Dan Williams dan.j.williams@intel.com Cc: Rasmus Villemoes rasmus.villemoes@prevas.dk Cc: Greg KH gregkh@linuxfoundation.org Cc: stable@vger.kernel.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: David Woodhouse dwmw@amazon.co.uk Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1802151718320.1296@nanos.tec.linut... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/time/posix-timers.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
--- 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 +1347,15 @@ static const struct k_clock * const posi
static const struct k_clock *clockid_to_kclock(const clockid_t id) { - if (id < 0) + 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]) + if (id >= ARRAY_SIZE(posix_clocks)) return NULL; - return posix_clocks[id]; + + return posix_clocks[array_index_nospec(idx, ARRAY_SIZE(posix_clocks))]; }
Patches currently in stable-queue which might be from tglx@linutronix.de are
queue-4.15/x86-entry-64-don-t-use-ist-entry-for-bp-stack.patch queue-4.15/selftests-x86-ptrace_syscall-fix-for-yet-more-glibc-interference.patch queue-4.15/posix-timers-protect-posix-clock-array-access-against-speculation.patch queue-4.15/x86-efi-free-efi_pgd-with-free_pages.patch queue-4.15/x86-vsyscall-64-use-proper-accessor-to-update-p4d-entry.patch queue-4.15/mm-vmalloc-add-interfaces-to-free-unmapped-page-table.patch queue-4.15/x86-mm-implement-free-pmd-pte-page-interfaces.patch