Patch "x86/syscall: Sanitize syscall table de-references under speculation" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    x86/syscall: Sanitize syscall table de-references under speculation

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-syscall-sanitize-syscall-table-de-references-under-speculation.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 foo@baz Fri Feb 23 17:23:58 CET 2018
From: Jack Wang <jinpu.wang@profitbricks.com>
Date: Fri, 23 Feb 2018 11:42:04 +0100
Subject: x86/syscall: Sanitize syscall table de-references under speculation
To: gregkh@linuxfoundation.org, stable@vger.kernel.org
Cc: Dan Williams <dan.j.williams@intel.com>, Thomas Gleixner <tglx@linutronix.de>, linux-arch@vger.kernel.org, kernel-hardening@lists.openwall.com, Andy Lutomirski <luto@kernel.org>, alan@linux.intel.com, David Woodhouse <dwmw@amazon.co.uk>, Jack Wang <jinpu.wang@profitbricks.com>
Message-ID: <1519382538-15143-16-git-send-email-jinpu.wangl@profitbricks.com>

From: Dan Williams <dan.j.williams@intel.com>

(cherry picked from commit 2fbd7af5af8665d18bcefae3e9700be07e22b681)

The syscall table base is a user controlled function pointer in kernel
space. Use array_index_nospec() to prevent any out of bounds speculation.

While retpoline prevents speculating into a userspace directed target it
does not stop the pointer de-reference, the concern is leaking memory
relative to the syscall table base, by observing instruction cache
behavior.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: kernel-hardening@lists.openwall.com
Cc: gregkh@linuxfoundation.org
Cc: Andy Lutomirski <luto@kernel.org>
Cc: alan@linux.intel.com
Link: https://lkml.kernel.org/r/151727417984.33451.1216731042505722161.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
[jwang: port to 4.4, no syscall_64]
Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/entry/common.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -20,6 +20,7 @@
 #include <linux/export.h>
 #include <linux/context_tracking.h>
 #include <linux/user-return-notifier.h>
+#include <linux/nospec.h>
 #include <linux/uprobes.h>
 
 #include <asm/desc.h>
@@ -381,6 +382,7 @@ __always_inline void do_syscall_32_irqs_
 	}
 
 	if (likely(nr < IA32_NR_syscalls)) {
+		nr = array_index_nospec(nr, IA32_NR_syscalls);
 		/*
 		 * It's possible that a 32-bit syscall implementation
 		 * takes a 64-bit parameter but nonetheless assumes that


Patches currently in stable-queue which might be from jinpu.wang@profitbricks.com are

queue-4.4/x86-paravirt-remove-noreplace-paravirt-cmdline-option.patch
queue-4.4/documentation-document-array_index_nospec.patch
queue-4.4/kvm-x86-make-indirect-calls-in-emulator-speculation-safe.patch
queue-4.4/x86-nospec-fix-header-guards-names.patch
queue-4.4/x86-retpoline-avoid-retpolines-for-built-in-__init-functions.patch
queue-4.4/vfs-fdtable-prevent-bounds-check-bypass-via-speculative-execution.patch
queue-4.4/kvm-nvmx-invvpid-handling-improvements.patch
queue-4.4/x86-cpu-bugs-make-retpoline-module-warning-conditional.patch
queue-4.4/x86-spectre-check-config_retpoline-in-command-line-parser.patch
queue-4.4/x86-implement-array_index_mask_nospec.patch
queue-4.4/array_index_nospec-sanitize-speculative-array-de-references.patch
queue-4.4/kvm-vmx-make-indirect-call-speculation-safe.patch
queue-4.4/x86-spectre-fix-spelling-mistake-vunerable-vulnerable.patch
queue-4.4/kvm-nvmx-fix-kernel-panics-induced-by-illegal-invept-invvpid-types.patch
queue-4.4/module-retpoline-warn-about-missing-retpoline-in-module.patch
queue-4.4/x86-kvm-update-spectre-v1-mitigation.patch
queue-4.4/x86-get_user-use-pointer-masking-to-limit-speculation.patch
queue-4.4/x86-syscall-sanitize-syscall-table-de-references-under-speculation.patch
queue-4.4/kvm-nvmx-vmx_complete_nested_posted_interrupt-can-t-fail.patch
queue-4.4/x86-spectre-simplify-spectre_v2-command-line-parsing.patch
queue-4.4/x86-speculation-fix-typo-ibrs_att-which-should-be-ibrs_all.patch
queue-4.4/x86-spectre-report-get_user-mitigation-for-spectre_v1.patch
queue-4.4/x86-introduce-barrier_nospec.patch
queue-4.4/kvm-async_pf-fix-df-due-to-inject-page-not-present-and-page-ready-exceptions-simultaneously.patch
queue-4.4/kvm-vmx-clean-up-declaration-of-vpid-ept-invalidation-types.patch
queue-4.4/x86-bugs-drop-one-mitigation-from-dmesg.patch
queue-4.4/x86-retpoline-remove-the-esp-rsp-thunk.patch
queue-4.4/nl80211-sanitize-array-index-in-parse_txq_params.patch
queue-4.4/kvm-nvmx-kmap-can-t-fail.patch