Patch "x86/microcode/intel: Guard against stack overflow in the loader" has been added to the 3.14-stable tree

Patch "x86/microcode/intel: Guard against stack overflow in the loader" has been added to the 3.14-stable tree

[gregkh]

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

    x86/microcode/intel: Guard against stack overflow in the loader

to the 3.14-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-microcode-intel-guard-against-stack-overflow-in-the-loader.patch
and it can be found in the queue-3.14 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 f84598bd7c851f8b0bf8cd0d7c3be0d73c432ff4 Mon Sep 17 00:00:00 2001
From: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Date: Tue, 3 Feb 2015 13:00:22 +0100
Subject: x86/microcode/intel: Guard against stack overflow in the loader

From: Quentin Casasnovas <quentin.casasnovas@oracle.com>

commit f84598bd7c851f8b0bf8cd0d7c3be0d73c432ff4 upstream.

mc_saved_tmp is a static array allocated on the stack, we need to make
sure mc_saved_count stays within its bounds, otherwise we're overflowing
the stack in _save_mc(). A specially crafted microcode header could lead
to a kernel crash or potentially kernel execution.

Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Link: http://lkml.kernel.org/r/1422964824-22056-1-git-send-email-quentin.casasnovas@oracle.com
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kernel/cpu/microcode/intel_early.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/microcode/intel_early.c
+++ b/arch/x86/kernel/cpu/microcode/intel_early.c
@@ -321,7 +321,7 @@ get_matching_model_microcode(int cpu, un
 	unsigned int mc_saved_count = mc_saved_data->mc_saved_count;
 	int i;
 
-	while (leftover) {
+	while (leftover && mc_saved_count < ARRAY_SIZE(mc_saved_tmp)) {
 		mc_header = (struct microcode_header_intel *)ucode_ptr;
 
 		mc_size = get_totalsize(mc_header);


Patches currently in stable-queue which might be from quentin.casasnovas@oracle.com are

queue-3.14/x86-microcode-intel-guard-against-stack-overflow-in-the-loader.patch