Re: [PATCH v5 5/7] mm, kasan: Stackdepot implementation. Enable stackdepot for SLAB
From: Andrew Morton
Date: Wed Mar 09 2016 - 15:09:42 EST
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
> 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?
> --- /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
> +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);
> 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
> +config STACKDEPOT
> + bool
> 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
> 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.