This is a note to let you know that I've just added the patch titled
nospec: Move array_index_nospec() parameter checking into separate macro
to the 4.4-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: nospec-move-array_index_nospec-parameter-checking-into-separate-macro.patch and it can be found in the queue-4.4 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 8fa80c503b484ddc1abbd10c7cb2ab81f3824a50 Mon Sep 17 00:00:00 2001
From: Will Deacon will.deacon@arm.com Date: Mon, 5 Feb 2018 14:16:06 +0000 Subject: nospec: Move array_index_nospec() parameter checking into separate macro
From: Will Deacon will.deacon@arm.com
commit 8fa80c503b484ddc1abbd10c7cb2ab81f3824a50 upstream.
For architectures providing their own implementation of array_index_mask_nospec() in asm/barrier.h, attempting to use WARN_ONCE() to complain about out-of-range parameters using WARN_ON() results in a mess of mutually-dependent include files.
Rather than unpick the dependencies, simply have the core code in nospec.h perform the checking for us.
Signed-off-by: Will Deacon will.deacon@arm.com Acked-by: Thomas Gleixner tglx@linutronix.de Cc: Dan Williams dan.j.williams@intel.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Link: http://lkml.kernel.org/r/1517840166-15399-1-git-send-email-will.deacon@arm.c... Signed-off-by: Ingo Molnar mingo@kernel.org Cc: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/nospec.h | 36 +++++++++++++++++++++--------------- 1 file changed, 21 insertions(+), 15 deletions(-)
--- a/include/linux/nospec.h +++ b/include/linux/nospec.h @@ -21,20 +21,6 @@ static inline unsigned long array_index_ unsigned long size) { /* - * Warn developers about inappropriate array_index_nospec() usage. - * - * Even if the CPU speculates past the WARN_ONCE branch, the - * sign bit of @index is taken into account when generating the - * mask. - * - * This warning is compiled out when the compiler can infer that - * @index and @size are less than LONG_MAX. - */ - if (WARN_ONCE(index > LONG_MAX || size > LONG_MAX, - "array_index_nospec() limited to range of [0, LONG_MAX]\n")) - return 0; - - /* * Always calculate and emit the mask even if the compiler * thinks the mask is not needed. The compiler does not take * into account the value of @index under speculation. @@ -45,6 +31,26 @@ static inline unsigned long array_index_ #endif
/* + * Warn developers about inappropriate array_index_nospec() usage. + * + * Even if the CPU speculates past the WARN_ONCE branch, the + * sign bit of @index is taken into account when generating the + * mask. + * + * This warning is compiled out when the compiler can infer that + * @index and @size are less than LONG_MAX. + */ +#define array_index_mask_nospec_check(index, size) \ +({ \ + if (WARN_ONCE(index > LONG_MAX || size > LONG_MAX, \ + "array_index_nospec() limited to range of [0, LONG_MAX]\n")) \ + _mask = 0; \ + else \ + _mask = array_index_mask_nospec(index, size); \ + _mask; \ +}) + +/* * array_index_nospec - sanitize an array index after a bounds check * * For a code sequence like: @@ -62,7 +68,7 @@ static inline unsigned long array_index_ ({ \ typeof(index) _i = (index); \ typeof(size) _s = (size); \ - unsigned long _mask = array_index_mask_nospec(_i, _s); \ + unsigned long _mask = array_index_mask_nospec_check(_i, _s); \ \ BUILD_BUG_ON(sizeof(_i) > sizeof(long)); \ BUILD_BUG_ON(sizeof(_s) > sizeof(long)); \
Patches currently in stable-queue which might be from will.deacon@arm.com are
queue-4.4/arm64-avoid-overflow-in-va_start-and-page_offset.patch queue-4.4/nospec-move-array_index_nospec-parameter-checking-into-separate-macro.patch queue-4.4/nospec-kill-array_index_nospec_mask_check.patch