Re: [PATCH v5 5/7] mm, kasan: Stackdepot implementation. Enable stackdepot for SLAB

[Alexander Potapenko]

On Wed, Mar 9, 2016 at 9:09 PM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Wed,  9 Mar 2016 12:05:46 +0100 Alexander Potapenko <glider@xxxxxxxxxx> wrote:
>
>> Implement the stack depot and provide CONFIG_STACKDEPOT.
>> Stack depot will allow KASAN store allocation/deallocation stack traces
>> for memory chunks. The stack traces are stored in a hash table and
>> referenced by handles which reside in the kasan_alloc_meta and
>> kasan_free_meta structures in the allocated memory chunks.
>>
>> IRQ stack traces are cut below the IRQ entry point to avoid unnecessary
>> duplication.
>>
>> Right now stackdepot support is only enabled in SLAB allocator.
>> Once KASAN features in SLAB are on par with those in SLUB we can switch
>> SLUB to stackdepot as well, thus removing the dependency on SLUB stack
>> bookkeeping, which wastes a lot of memory.
>>
>> This patch is based on the "mm: kasan: stack depots" patch originally
>> prepared by Dmitry Chernenkov.
>>
>
> Have you identified other potential clients for the stackdepot code?
Joonsoo Kim said he is planning to use stackdepot for the page owner.
>> --- /dev/null
>> +++ b/include/linux/stackdepot.h
>> @@ -0,0 +1,32 @@
>> +/*
>> + * A generic stack depot implementation
>> + *
>> + * Author: Alexander Potapenko <glider@xxxxxxxxxx>
>> + * Copyright (C) 2016 Google, Inc.
>> + *
>> + * Based on code by Dmitry Chernenkov.
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + *
>> + */
>> +
>> +#ifndef _LINUX_STACKDEPOT_H
>> +#define _LINUX_STACKDEPOT_H
>> +
>> +typedef u32 depot_stack_handle;
>
> I'll rename this to depot_stack_handle_t, which is a pretty strong
> kernel convention.
Ok, thank you!
>> +struct stack_trace;
>> +
>> +depot_stack_handle depot_save_stack(struct stack_trace *trace, gfp_t flags);
>> +
>> +void depot_fetch_stack(depot_stack_handle handle, struct stack_trace *trace);
>> +
>> +#endif
>> diff --git a/lib/Kconfig b/lib/Kconfig
>> index ee38a3f..8a60a53 100644
>> --- a/lib/Kconfig
>> +++ b/lib/Kconfig
>> @@ -543,4 +543,7 @@ config ARCH_HAS_PMEM_API
>>  config ARCH_HAS_MMIO_FLUSH
>>       bool
>>
>> +config STACKDEPOT
>> +  bool
>> +
>>  endmenu
>> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
>> index 0e4d2b3..468316d 100644
>> --- a/lib/Kconfig.kasan
>> +++ b/lib/Kconfig.kasan
>> @@ -7,6 +7,7 @@ config KASAN
>>       bool "KASan: runtime memory debugger"
>>       depends on SLUB_DEBUG || (SLAB && !DEBUG_SLAB)
>>       select CONSTRUCTORS
>> +  select STACKDEPOT if SLAB
>>       help
>>         Enables kernel address sanitizer - runtime memory debugger,
>>         designed to find out-of-bounds accesses and use-after-free bugs.
>
> Something weird happened to the Kconfig whitespace.  I'll fix that.
Thanks!
>



-- 
Alexander Potapenko
Software Engineer

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