linux-kernel - [ 17/85] x86, amd, mce: Avoid NULL pointer reference on CPU northbridge lookup

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20121026000032.855552613@linuxfoundation.org>
Date:	Thu, 25 Oct 2012 17:05:35 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk,
	Daniel J Blueman <daniel@...ascale-asia.com>,
	Borislav Petkov <borislav.petkov@....com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: [ 17/85] x86, amd, mce: Avoid NULL pointer reference on CPU northbridge lookup

3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel J Blueman <daniel@...ascale-asia.com>

commit 21c5e50e15b1abd797e62f18fd7f90b9cc004cbd upstream.

When booting on a federated multi-server system (NumaScale), the
processor Northbridge lookup returns NULL; add guards to prevent this
causing an oops.

On those systems, the northbridge is accessed through MMIO and the
"normal" northbridge enumeration in amd_nb.c doesn't work since we're
generating the northbridge ID from the initial APIC ID and the last
is not unique on those systems. Long story short, we end up without
northbridge descriptors.

Signed-off-by: Daniel J Blueman <daniel@...ascale-asia.com>
Link: http://lkml.kernel.org/r/1349073725-14093-1-git-send-email-daniel@numascale-asia.com
[ Boris: beef up commit message ]
Signed-off-by: Borislav Petkov <borislav.petkov@....com>
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/kernel/cpu/mcheck/mce_amd.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -576,12 +576,10 @@ static __cpuinit int threshold_create_ba
 	int err = 0;

 	if (shared_bank[bank]) {
-
 		nb = node_to_amd_nb(amd_get_nb_id(cpu));
-		WARN_ON(!nb);

 		/* threshold descriptor already initialized on this node? */
-		if (nb->bank4) {
+		if (nb && nb->bank4) {
 			/* yes, use it */
 			b = nb->bank4;
 			err = kobject_add(b->kobj, &dev->kobj, name);
@@ -615,8 +613,10 @@ static __cpuinit int threshold_create_ba
 		atomic_set(&b->cpus, 1);

 		/* nb is already initialized, see above */
-		WARN_ON(nb->bank4);
-		nb->bank4 = b;
+		if (nb) {
+			WARN_ON(nb->bank4);
+			nb->bank4 = b;
+		}
 	}

 	err = allocate_threshold_blocks(cpu, bank, 0,

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/