Patch "vfs, fdtable: Prevent bounds-check bypass via speculative execution" has been added to the 4.9-stable tree

Patch "vfs, fdtable: Prevent bounds-check bypass via speculative execution" has been added to the 4.9-stable tree

[gregkh]

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

    vfs, fdtable: Prevent bounds-check bypass via speculative execution

to the 4.9-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:
     vfs-fdtable-prevent-bounds-check-bypass-via-speculative-execution.patch
and it can be found in the queue-4.9 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 Thu Feb  8 03:32:24 CET 2018
From: Dan Williams <dan.j.williams@intel.com>
Date: Mon, 29 Jan 2018 17:03:05 -0800
Subject: vfs, fdtable: Prevent bounds-check bypass via speculative execution

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


(cherry picked from commit 56c30ba7b348b90484969054d561f711ba196507)

'fd' is a user controlled value that is used as a data dependency to
read from the 'fdt->fd' array.  In order to avoid potential leaks of
kernel memory values, block speculative execution of the instruction
stream that could issue reads based on an invalid 'file *' returned from
__fcheck_files.

Co-developed-by: Elena Reshetova <elena.reshetova@intel.com>
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: Al Viro <viro@zeniv.linux.org.uk>
Cc: torvalds@linux-foundation.org
Cc: alan@linux.intel.com
Link: https://lkml.kernel.org/r/151727418500.33451.17392199002892248656.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 include/linux/fdtable.h |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -9,6 +9,7 @@
 #include <linux/compiler.h>
 #include <linux/spinlock.h>
 #include <linux/rcupdate.h>
+#include <linux/nospec.h>
 #include <linux/types.h>
 #include <linux/init.h>
 #include <linux/fs.h>
@@ -81,8 +82,10 @@ static inline struct file *__fcheck_file
 {
 	struct fdtable *fdt = rcu_dereference_raw(files->fdt);
 
-	if (fd < fdt->max_fds)
+	if (fd < fdt->max_fds) {
+		fd = array_index_nospec(fd, fdt->max_fds);
 		return rcu_dereference_raw(fdt->fd[fd]);
+	}
 	return NULL;
 }
 


Patches currently in stable-queue which might be from dan.j.williams@intel.com are

queue-4.9/kvm-vmx-allow-direct-access-to-msr_ia32_spec_ctrl.patch
queue-4.9/kvm-x86-add-ibpb-support.patch
queue-4.9/kvm-svm-allow-direct-access-to-msr_ia32_spec_ctrl.patch
queue-4.9/x86-paravirt-remove-noreplace-paravirt-cmdline-option.patch
queue-4.9/documentation-document-array_index_nospec.patch
queue-4.9/x86-usercopy-replace-open-coded-stac-clac-with-__uaccess_-begin-end.patch
queue-4.9/kvm-x86-make-indirect-calls-in-emulator-speculation-safe.patch
queue-4.9/vfs-fdtable-prevent-bounds-check-bypass-via-speculative-execution.patch
queue-4.9/x86-uaccess-use-__uaccess_begin_nospec-and-uaccess_try_nospec.patch
queue-4.9/x86-implement-array_index_mask_nospec.patch
queue-4.9/array_index_nospec-sanitize-speculative-array-de-references.patch
queue-4.9/kvm-vmx-make-indirect-call-speculation-safe.patch
queue-4.9/x86-kvm-update-spectre-v1-mitigation.patch
queue-4.9/x86-get_user-use-pointer-masking-to-limit-speculation.patch
queue-4.9/x86-syscall-sanitize-syscall-table-de-references-under-speculation.patch
queue-4.9/x86-spectre-report-get_user-mitigation-for-spectre_v1.patch
queue-4.9/x86-introduce-barrier_nospec.patch
queue-4.9/kvm-vmx-emulate-msr_ia32_arch_capabilities.patch
queue-4.9/x86-introduce-__uaccess_begin_nospec-and-uaccess_try_nospec.patch
queue-4.9/nl80211-sanitize-array-index-in-parse_txq_params.patch