[3.16.y-ckt stable] Patch "EDAC, amd64_edac: Prevent OOPS with >16 memory controllers" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    EDAC, amd64_edac: Prevent OOPS with >16 memory controllers

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 2982c0dc3313076bd32227590f7a0a138f8aba02 Mon Sep 17 00:00:00 2001
From: Daniel J Blueman <daniel at numascale.com>
Date: Tue, 17 Feb 2015 11:34:38 +0800
Subject: EDAC, amd64_edac: Prevent OOPS with >16 memory controllers

commit 0c510cc83bdbaac8406f4f7caef34f4da0ba35ea upstream.

When DRAM errors occur on memory controllers after EDAC_MAX_MCS (16),
the kernel fatally dereferences unallocated structures, see splat below;
this occurs on at least NumaConnect systems.

Fix by checking if a memory controller info structure was found.

BUG: unable to handle kernel NULL pointer dereference at 0000000000000320
IP: [<ffffffff819f714f>] decode_bus_error+0x2f/0x2b0
PGD 2f8b5a3067 PUD 2f8b5a2067 PMD 0
Oops: 0000 [#2] SMP
Modules linked in:
CPU: 224 PID: 11930 Comm: stream_c.exe.gn Tainted: G   D    3.19.0 #1
Hardware name: Supermicro H8QGL/H8QGL, BIOS 3.5b    01/28/2015
task: ffff8807dbfb8c00 ti: ffff8807dd16c000 task.ti: ffff8807dd16c000
RIP: 0010:[<ffffffff819f714f>] [<ffffffff819f714f>] decode_bus_error+0x2f/0x2b0
RSP: 0000:ffff8907dfc03c48 EFLAGS: 00010297
RAX: 0000000000000001 RBX: 9c67400010080a13 RCX: 0000000000001dc6
RDX: 000000001dc61dc6 RSI: ffff8907dfc03df0 RDI: 000000000000001c
RBP: ffff8907dfc03ce8 R08: 0000000000000000 R09: 0000000000000022
R10: ffff891fffa30380 R11: 00000000001cfc90 R12: 0000000000000008
R13: 0000000000000000 R14: 000000000000001c R15: 00009c6740001000
FS: 00007fa97ee18700(0000) GS:ffff8907dfc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000320 CR3: 0000003f889b8000 CR4: 00000000000407e0
Stack:
 0000000000000000 ffff8907dfc03df0 0000000000000008 9c67400010080a13
 000000000000001c 00009c6740001000 ffff8907dfc03c88 ffffffff810e4f9a
 ffff8907dfc03ce8 ffffffff81b375b9 0000000000000000 0000000000000010
Call Trace:
 <IRQ>
 ? vprintk_default
 ? printk
 amd_decode_mce
 notifier_call_chain
 atomic_notifier_call_chain
 mce_log
 machine_check_poll
 mce_timer_fn
 ? mce_cpu_restart
 call_timer_fn.isra.29
 run_timer_softirq
 __do_softirq
 irq_exit
 smp_apic_timer_interrupt
 apic_timer_interrupt
 <EOI>
 ? down_read_trylock
 __do_page_fault
 ? __schedule
 do_page_fault
 page_fault

Signed-off-by: Daniel J Blueman <daniel at numascale.com>
Link: http://lkml.kernel.org/r/1424144078-24589-1-git-send-email-daniel@numascale.com
[ Boris: massage commit message ]
Signed-off-by: Borislav Petkov <bp at suse.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/edac/amd64_edac.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
index f8bf00010d45..4af3ae4fcd96 100644
--- a/drivers/edac/amd64_edac.c
+++ b/drivers/edac/amd64_edac.c
@@ -2025,14 +2025,20 @@ static void __log_bus_error(struct mem_ctl_info *mci, struct err_info *err,

 static inline void decode_bus_error(int node_id, struct mce *m)
 {
-	struct mem_ctl_info *mci = mcis[node_id];
-	struct amd64_pvt *pvt = mci->pvt_info;
+	struct mem_ctl_info *mci;
+	struct amd64_pvt *pvt;
 	u8 ecc_type = (m->status >> 45) & 0x3;
 	u8 xec = XEC(m->status, 0x1f);
 	u16 ec = EC(m->status);
 	u64 sys_addr;
 	struct err_info err;

+	mci = edac_mc_find(node_id);
+	if (!mci)
+		return;
+
+	pvt = mci->pvt_info;
+
 	/* Bail out early if this was an 'observed' error */
 	if (PP(ec) == NBSL_PP_OBS)
 		return;