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Patch "x86/microcode/intel: Guard against stack overflow in the loader" has been added to the 3.10-stable tree

PATCH [email protected] 1 participant 1 message Jun 30, 2015

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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 3.10-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-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From c5988181af3b41381c4d20e08ca6852f99f95417 Mon Sep 17 00:00:00 2001

From: Quentin Casasnovas <[email protected]>
Date: Tue, 3 Feb 2015 13:00:22 +0100
Subject: x86/microcode/intel: Guard against stack overflow in the loader

From: Quentin Casasnovas <[email protected]>

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.

---
 arch/x86/kernel/microcode_intel_early.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/kernel/microcode_intel_early.c +1 -1
@@ -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 [email protected] are

queue-3.10/x86-microcode-intel-guard-against-stack-overflow-in-the-loader.patch