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Date: Sun, 26 Jul 2015 10:13:45 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: =?ISO-8859-15?Q?Philip_M=FCller?= <philm@manjaro.org>
cc: linux-kernel@vger.kernel.org, Sudeep Holla <sudeep.holla@arm.com>,
        Guenter Roeck <linux@roeck-us.net>, manjaro-dev@manjaro.org,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        Andre Przywara <andre.przywara@arm.com>, Borislav Petkov <bp@suse.de>
Subject: Re: [linux41] regression with 'x86/cacheinfo: Move cacheinfo sysfs
 code to generic infrastructure' on AMD i686
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Message-ID: <alpine.DEB.2.11.1507261012480.18576@nanos>
References: <55B16967.1040609@manjaro.org> <55B47BB8.6080202@manjaro.org>
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On Sun, 26 Jul 2015, Philip Müller wrote:
> > task: f58e0000 ti: f58e8000 task.ti: f58e800
> > EIP: 0060:[<c135a903>] EFLAGS: 00010206 CPU: 0
> > EIP is at free_cache_attributes+0x83/0xd0
> > EAX: 00000001 EBX: f589d46c ECX: 00000090 EDX: 360c2000
> > ESI: 00000000 EDI: c1724a80 EBP: f58e9ec0 ESP: f58e9ea0
> >  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
> > CR0: 8005003b CR2: 000000ac CR3: 01731000 CR4: 000006d0

That's a trivial NULL pointer dereference in the error/cleanup
path. Patch below should fix it.

Thanks,

	tglx
---
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 764280a91776..f09b106d8b81 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -159,6 +159,9 @@ static void cache_shared_cpu_map_remove(unsigned int cpu)
 
 static void free_cache_attributes(unsigned int cpu)
 {
+	if (!per_cpu_cacheinfo(cpu))
+		return;
+
 	cache_shared_cpu_map_remove(cpu);
 
 	kfree(per_cpu_cacheinfo(cpu));
@@ -514,8 +517,7 @@ static int cacheinfo_cpu_callback(struct notifier_block *nfb,
 		break;
 	case CPU_DEAD:
 		cache_remove_dev(cpu);
-		if (per_cpu_cacheinfo(cpu))
-			free_cache_attributes(cpu);
+		free_cache_attributes(cpu);
 		break;
 	}
 	return notifier_from_errno(rc);
--8323329-294823616-1437898426=:18576--
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