[tip:ras/core] x86/mce: Do not register notifiers with invalid prio

From: tip-bot for Borislav Petkov
Date: Tue Mar 28 2017 - 03:08:01 EST


Commit-ID: 32b40a82e84414499bb4d635cafb9de9e45e6c38
Gitweb: http://git.kernel.org/tip/32b40a82e84414499bb4d635cafb9de9e45e6c38
Author: Borislav Petkov <bp@xxxxxxx>
AuthorDate: Mon, 27 Mar 2017 11:33:04 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 28 Mar 2017 08:55:15 +0200

x86/mce: Do not register notifiers with invalid prio

This is just a defensive precaution: do not register notifiers with a
priority which would disrupt the error handling in the notifiers with
prio higher than MCE_PRIO_EDAC.

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-edac <linux-edac@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170327093304.10683-7-bp@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/kernel/cpu/mcheck/mce.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 36082c7..a09bb67 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -157,9 +157,10 @@ static atomic_t num_notifiers;

void mce_register_decode_chain(struct notifier_block *nb)
{
- atomic_inc(&num_notifiers);
+ if (WARN_ON(nb->priority > MCE_PRIO_LOWEST && nb->priority < MCE_PRIO_EDAC))
+ return;

- WARN_ON(nb->priority > MCE_PRIO_LOWEST && nb->priority < MCE_PRIO_EDAC);
+ atomic_inc(&num_notifiers);

atomic_notifier_chain_register(&x86_mce_decoder_chain, nb);
}