Commit 5ba6a2f4 authored Feb 03, 2015 by Quentin Casasnovas Committed by Sasha Levin Jul 13, 2015

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



[ Upstream commit f84598bd7c851f8b0bf8cd0d7c3be0d73c432ff4 ]

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: Sasha Levin <sasha.levin@oracle.com>

parent ab297a49

arch/x86/kernel/cpu/microcode/intel_early.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -321,7 +321,7 @@ get_matching_model_microcode(int cpu, unsigned long start,
		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);