Re: [PATCH V2] x86/numa: kernel stack corruption fix

[Xishi Qiu <qiuxishi@huawei.com>]

On 2015/4/7 21:41, Dave Young wrote:

> 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@redhat.com>
> Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.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

Hi Dave,

It should both set mem=xx and numa=off, then numa_meminfo may not include all
the memblock.reserved memory, right?

Thanks,
Xishi Qiu

> +	 * 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++) {
> 
> .
>