linux-kernel - Re: [PATCH] EDAC, MCE, AMD: Fix code to prevent NULL dereference

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Message-ID: <20140218084636.GA24465@pd.tnic>
Date:	Tue, 18 Feb 2014 09:46:36 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Aravind Gopalakrishnan <aravind.gopalakrishnan@....com>
Cc:	dougthompson@...ssion.com, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] EDAC, MCE, AMD: Fix code to prevent NULL dereference

Ok, let's try a simpler thing. Only build-tested here:

---
diff --git a/drivers/edac/mce_amd.c b/drivers/edac/mce_amd.c
index 30f7309446a6..30592838f1da 100644
--- a/drivers/edac/mce_amd.c
+++ b/drivers/edac/mce_amd.c
@@ -738,6 +738,9 @@ int amd_decode_mce(struct notifier_block *nb, unsigned long val, void *data)
 	struct cpuinfo_x86 *c = &cpu_data(m->extcpu);
 	int ecc;
 
+	if (!fam_ops)
+		return NOTIFY_DONE;
+
 	if (amd_filter_mce(m))
 		return NOTIFY_STOP;
 
@@ -816,10 +819,10 @@ static int __init mce_amd_init(void)
 	struct cpuinfo_x86 *c = &boot_cpu_data;
 
 	if (c->x86_vendor != X86_VENDOR_AMD)
-		return 0;
+		return -ENODEV;
 
 	if (c->x86 < 0xf || c->x86 > 0x16)
-		return 0;
+		return -ENODEV;
 
 	fam_ops = kzalloc(sizeof(struct amd_decoder_ops), GFP_KERNEL);
 	if (!fam_ops)
@@ -874,6 +877,7 @@ static int __init mce_amd_init(void)
 	default:
 		printk(KERN_WARNING "Huh? What family is it: 0x%x?!\n", c->x86);
 		kfree(fam_ops);
+		fam_ops = NULL;
 		return -EINVAL;
 	}
 

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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