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Date:	Tue, 7 Apr 2015 21:41:32 +0800
From:	Dave Young <dyoung@...hat.com>
To:	x86@...nel.org, linux-kernel@...r.kernel.org, tglx@...utronix.de,
	bhe@...hat.com, akpm@...ux-foundation.org,
	isimatu.yasuaki@...fujitsu.com, qiuxishi@...wei.com
Cc:	mingo@...hat.com, hpa@...or.com
Subject: [PATCH V2] x86/numa: kernel stack corruption fix

I got below kernel panic during kdump test on Thinkpad T420 laptop:

[    0.000000] No NUMA configuration found                                      
[    0.000000] Faking a node at [mem 0x0000000000000000-0x0000000037ba4fff]     
[    0.000000] Kernel panic - not syncing: stack-protector: Kernel stack is cor 
upted in: ffffffff81d21910                                                     r
[    0.000000]                                                                  
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.0.0-rc6+ #44           
[    0.000000] Hardware name: LENOVO 4236NUC/4236NUC, BIOS 83ET76WW (1.46 ) 07/ 
5/2013                                                                         0
[    0.000000]  0000000000000000 c70296ddd809e4f6 ffffffff81b67ce8 ffffffff817c 
a26                                                                            2
[    0.000000]  0000000000000000 ffffffff81a61c90 ffffffff81b67d68 ffffffff817b 
8d2                                                                            c
[    0.000000]  0000000000000010 ffffffff81b67d78 ffffffff81b67d18 c70296ddd809 
4f6                                                                            e
[    0.000000] Call Trace:                                                      
[    0.000000]  [<ffffffff817c2a26>] dump_stack+0x45/0x57                       
[    0.000000]  [<ffffffff817bc8d2>] panic+0xd0/0x204                           
[    0.000000]  [<ffffffff81d21910>] ? numa_clear_kernel_node_hotplug+0xe6/0xf2 
[    0.000000]  [<ffffffff8107741b>] __stack_chk_fail+0x1b/0x20                 
[    0.000000]  [<ffffffff81d21910>] numa_clear_kernel_node_hotplug+0xe6/0xf2   
[    0.000000]  [<ffffffff81d21e5d>] numa_init+0x1a5/0x520                      
[    0.000000]  [<ffffffff81d222b1>] x86_numa_init+0x19/0x3d                    
[    0.000000]  [<ffffffff81d22460>] initmem_init+0x9/0xb                       
[    0.000000]  [<ffffffff81d0d00c>] setup_arch+0x94f/0xc82                     
[    0.000000]  [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120           
[    0.000000]  [<ffffffff817bd0bb>] ? printk+0x55/0x6b                         
[    0.000000]  [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120           
[    0.000000]  [<ffffffff81d05d9b>] start_kernel+0xe8/0x4d6                    
[    0.000000]  [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120           
[    0.000000]  [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120           
[    0.000000]  [<ffffffff81d055ee>] x86_64_start_reservations+0x2a/0x2c        
[    0.000000]  [<ffffffff81d05751>] x86_64_start_kernel+0x161/0x184            
[    0.000000] ---[ end Kernel panic - not syncing: stack-protector: Kernel sta 
k is corrupted in: ffffffff81d21910                                            c
[    0.000000]                                                                  
PANIC: early exception 0d rip 10:ffffffff8105d2a6 error 7eb cr2 ffff8800371dd00 
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.0.0-rc6+ #44          0
[    0.000000] Hardware name: LENOVO 4236NUC/4236NUC, BIOS 83ET76WW (1.46 ) 07/ 
5/2013                                                                         0
[    0.000000]  0000000000000000 c70296ddd809e4f6 ffffffff81b67c60 ffffffff817c 
a26                                                                            2
[    0.000000]  0000000000000096 ffffffff81a61c90 ffffffff81b67d68 fffffff00000 
084 0000000000000a0d 0000000000000a00                                          0
[    0.000000] Call Trace:                                                      
[    0.000000]  [<ffffffff817c2a26>] dump_stack+0x45/0x57                       
[    0.000000]  [<ffffffff81d051b0>] early_idt_handler+0x90/0xb7                
[    0.000000]  [<ffffffff8105d2a6>] ? native_irq_enable+0x6/0x10               
[    0.000000]  [<ffffffff817bc9c5>] ? panic+0x1c3/0x204                        
[    0.000000]  [<ffffffff81d21910>] ? numa_clear_kernel_node_hotplug+0xe6/0xf2 
[    0.000000]  [<ffffffff8107741b>] __stack_chk_fail+0x1b/0x20                 
[    0.000000]  [<ffffffff81d21910>] numa_clear_kernel_node_hotplug+0xe6/0xf2   
[    0.000000]  [<ffffffff81d21e5d>] numa_init+0x1a5/0x520                      
[    0.000000]  [<ffffffff81d222b1>] x86_numa_init+0x19/0x3d                    
[    0.000000]  [<ffffffff81d22460>] initmem_init+0x9/0xb                       
[    0.000000]  [<ffffffff81d0d00c>] setup_arch+0x94f/0xc82                     
[    0.000000]  [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120           
[    0.000000]  [<ffffffff817bd0bb>] ? printk+0x55/0x6b                         
[    0.000000]  [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120           
[    0.000000]  [<ffffffff81d05d9b>] start_kernel+0xe8/0x4d6                    
[    0.000000]  [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120           
[    0.000000]  [<ffffffff81d05120>] ? early_idt_handlers+0x120/0x120           
[    0.000000]  [<ffffffff81d055ee>] x86_64_start_reservations+0x2a/0x2c        
[    0.000000]  [<ffffffff81d05751>] x86_64_start_kernel+0x161/0x184            
[    0.000000] RIP 0x46                                                         

This is caused by writing over end of numa mask bitmap.

numa_clear_kernel_node try to set node id in a mask bitmap, it iterating all
reserved region and assume every regions have valid nid. It is not true because
There's an exception for some graphic memory quirks.
See function trim_snb_memory in arch/x86/kernel/setup.c

It is easily to reproduce the bug in kdump kernel because kdump kernel use
pre-reserved memory instead of whole memory, but kexec pass other reserved
memory ranges to 2nd kernel as well. like below in my test:

kdump kernel ram 0x2d000000 - 0x37bfffff
One of the reserved regions: 0x40000000 - 0x40100000 which includes 0x40004000,
a page excluded in trim_snb_memory. For this memblock reserved region the nid
is not set, it is still default value MAX_NUMNODES. later node_set will set bit
MAX_NUMNODES thus stack corruption happen. 

This also happens when booting with mem= kernel commandline during my test.

Fixing it by adding a check, do not call node_set in case nid is MAX_NUMNODES.

Signed-off-by: Dave Young <dyoung@...hat.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
---
 arch/x86/mm/numa.c |   11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

--- linux.orig/arch/x86/mm/numa.c
+++ linux/arch/x86/mm/numa.c
@@ -482,9 +482,16 @@ static void __init numa_clear_kernel_nod
 				  &memblock.reserved, mb->nid);
 	}
 
-	/* Mark all kernel nodes. */
+	/*
+	 * Mark all kernel nodes.
+	 *
+	 * In case booting with mem=nn[kMG] or in kdump kernel, numa_meminfo
+	 * may not include all the memblock.reserved memory ranges because
+	 * trim_snb_memory() reserves specific pages for Sandy Bridge graphics.
+	 */
 	for_each_memblock(reserved, r)
-		node_set(r->nid, numa_kernel_nodes);
+		if (r->nid != MAX_NUMNODES)
+			node_set(r->nid, numa_kernel_nodes);
 
 	/* Clear MEMBLOCK_HOTPLUG flag for memory in kernel nodes. */
 	for (i = 0; i < numa_meminfo.nr_blks; i++) {
--
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