This is a note to let you know that I've just added the patch titled
x86, microcode: Return error from driver init code when loader is disabled
to the 3.18-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-return-error-from-driver-init-code-when-loader-is-disabled.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From da63865a01c6384d459464e5165d95d4f04878d8 Mon Sep 17 00:00:00 2001
From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Date: Tue, 27 Jan 2015 21:21:09 -0500
Subject: x86, microcode: Return error from driver init code when loader is disabled
From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
commit da63865a01c6384d459464e5165d95d4f04878d8 upstream.
Commits 65cef1311d5d ("x86, microcode: Add a disable chicken bit") and
a18a0f6850d4 ("x86, microcode: Don't initialize microcode code on
paravirt") allow microcode driver skip initialization when microcode
loading is not permitted.
However, they don't prevent the driver from being loaded since the
init code returns 0. If at some point later the driver gets unloaded
this will result in an oops while trying to deregister the (never
registered) device.
To avoid this, make init code return an error on paravirt or when
microcode loading is disabled. The driver will then never be loaded.
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1422411669-25147-1-git-send-email-boris.ostrovsky@xxxxxxxxxx
Reported-by: James Digwall <james@xxxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/microcode/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -552,7 +552,7 @@ static int __init microcode_init(void)
int error;
if (paravirt_enabled() || dis_ucode_ldr)
- return 0;
+ return -EINVAL;
if (c->x86_vendor == X86_VENDOR_INTEL)
microcode_ops = init_intel_microcode();
Patches currently in stable-queue which might be from boris.ostrovsky@xxxxxxxxxx are
queue-3.18/x86-microcode-return-error-from-driver-init-code-when-loader-is-disabled.patch
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