linux-kernel - Re: [PATCH v11 1/4] kasan: support backing vmalloc space with real shadow memory

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Date:   Tue, 19 Nov 2019 12:54:08 +0300
From:   Andrey Ryabinin <aryabinin@...tuozzo.com>
To:     Daniel Axtens <dja@...ens.net>, Qian Cai <cai@....pw>,
        kasan-dev@...glegroups.com, linux-mm@...ck.org, x86@...nel.org,
        glider@...gle.com, luto@...nel.org, linux-kernel@...r.kernel.org,
        mark.rutland@....com, dvyukov@...gle.com, christophe.leroy@....fr
Cc:     linuxppc-dev@...ts.ozlabs.org, gor@...ux.ibm.com
Subject: Re: [PATCH v11 1/4] kasan: support backing vmalloc space with real
 shadow memory



On 11/18/19 6:29 AM, Daniel Axtens wrote:
> Qian Cai <cai@....pw> writes:
> 
>> On Thu, 2019-10-31 at 20:39 +1100, Daniel Axtens wrote:
>>>  	/*
>>>  	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
>>>  	 * flag. It means that vm_struct is not fully initialized.
>>> @@ -3377,6 +3411,9 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
>>>  
>>>  		setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
>>>  				 pcpu_get_vm_areas);
>>> +
>>> +		/* assume success here */
>>> +		kasan_populate_vmalloc(sizes[area], vms[area]);
>>>  	}
>>>  	spin_unlock(&vmap_area_lock);
>>
>> Here it is all wrong. GFP_KERNEL with in_atomic().
> 
> I think this fix will work, I will do a v12 with it included.
 
You can send just the fix. Andrew will fold it into the original patch before sending it to Linus.



> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index a4b950a02d0b..bf030516258c 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -3417,11 +3417,14 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
>  
>                 setup_vmalloc_vm_locked(vms[area], vas[area], VM_ALLOC,
>                                  pcpu_get_vm_areas);
> +       }
> +       spin_unlock(&vmap_area_lock);
>  
> +       /* populate the shadow space outside of the lock */
> +       for (area = 0; area < nr_vms; area++) {
>                 /* assume success here */
>                 kasan_populate_vmalloc(sizes[area], vms[area]);
>         }
> -       spin_unlock(&vmap_area_lock);
>  
>         kfree(vas);
>         return vms;
> 
>