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x86, microcode: Return error from driver init code when loader is disabled

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Commits 65cef1311d ("x86, microcode: Add a disable chicken bit") and
a18a0f6850 ("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@oracle.com>
Link: http://lkml.kernel.org/r/1422411669-25147-1-git-send-email-boris.ostrovsky@oracle.com
Reported-by: James Digwall <james@dingwall.me.uk>
Cc: stable@vger.kernel.org # 3.18
Signed-off-by: Borislav Petkov <bp@suse.de>
This commit is contained in:
Boris Ostrovsky 2015-01-27 21:21:09 -05:00 committed by Borislav Petkov
parent 26bc420b59
commit da63865a01
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/cpu/microcode/core.c
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@ -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();