From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f46.google.com (mail-pa0-f46.google.com [209.85.220.46]) by kanga.kvack.org (Postfix) with ESMTP id 75B0D6B0032 for ; Fri, 30 Jan 2015 12:47:27 -0500 (EST) Received: by mail-pa0-f46.google.com with SMTP id lj1so54828248pab.5 for ; Fri, 30 Jan 2015 09:47:27 -0800 (PST) Received: from mailout3.w1.samsung.com (mailout3.w1.samsung.com. [210.118.77.13]) by mx.google.com with ESMTPS id u5si11283932pde.139.2015.01.30.09.47.26 for (version=TLSv1 cipher=RC4-MD5 bits=128/128); Fri, 30 Jan 2015 09:47:26 -0800 (PST) Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout3.w1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NJ000LIL49QU9B0@mailout3.w1.samsung.com> for linux-mm@kvack.org; Fri, 30 Jan 2015 17:51:26 +0000 (GMT) Message-id: <54CBC3A1.5040505@samsung.com> Date: Fri, 30 Jan 2015 20:47:13 +0300 From: Andrey Ryabinin MIME-version: 1.0 Subject: Re: [PATCH v10 17/17] kasan: enable instrumentation of global variables References: <1404905415-9046-1-git-send-email-a.ryabinin@samsung.com> <1422544321-24232-1-git-send-email-a.ryabinin@samsung.com> <1422544321-24232-18-git-send-email-a.ryabinin@samsung.com> <20150129151332.3f87c0b2e335afd88af33e08@linux-foundation.org> In-reply-to: <20150129151332.3f87c0b2e335afd88af33e08@linux-foundation.org> Content-type: text/plain; charset=windows-1252 Content-transfer-encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, Dmitry Vyukov , Konstantin Serebryany , Dmitry Chernenkov , Andrey Konovalov , Yuri Gribov , Konstantin Khlebnikov , Sasha Levin , Christoph Lameter , Joonsoo Kim , Dave Hansen , Andi Kleen , x86@kernel.org, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Rusty Russell , Michal Marek , "open list:KERNEL BUILD + fi..." On 01/30/2015 02:13 AM, Andrew Morton wrote: > On Thu, 29 Jan 2015 18:12:01 +0300 Andrey Ryabinin wrote: > >> This feature let us to detect accesses out of bounds >> of global variables. > > global variables *within modules*, I think? More specificity needed here. Within modules and within kernel image. Handling modules just the most tricky part of this. > >> The idea of this is simple. Compiler increases each global variable >> by redzone size and add constructors invoking __asan_register_globals() >> function. Information about global variable (address, size, >> size with redzone ...) passed to __asan_register_globals() so we could >> poison variable's redzone. >> >> This patch also forces module_alloc() to return 8*PAGE_SIZE aligned >> address making shadow memory handling ( kasan_module_alloc()/kasan_module_free() ) >> more simple. Such alignment guarantees that each shadow page backing >> modules address space correspond to only one module_alloc() allocation. >> >> ... >> >> +int kasan_module_alloc(void *addr, size_t size) >> +{ >> + >> + size_t shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT, >> + PAGE_SIZE); >> + unsigned long shadow_start = kasan_mem_to_shadow((unsigned long)addr); >> + void *ret; > > Like this: > > size_t shadow_size; > unsigned long shadow_start; > void *ret; > > shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT, PAGE_SIZE); > shadow_start = kasan_mem_to_shadow((unsigned long)addr); > > it's much easier to read and avoids the 80-column trickery. > > I do suspect that > > void *kasan_mem_to_shadow(const void *addr); > > would clean up lots and lots of code. > Agreed. >> + if (WARN_ON(!PAGE_ALIGNED(shadow_start))) >> + return -EINVAL; >> + >> + ret = __vmalloc_node_range(shadow_size, 1, shadow_start, >> + shadow_start + shadow_size, >> + GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, >> + PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE, >> + __builtin_return_address(0)); >> + return ret ? 0 : -ENOMEM; >> +} >> + >> >> ... >> >> +struct kasan_global { >> + const void *beg; /* Address of the beginning of the global variable. */ >> + size_t size; /* Size of the global variable. */ >> + size_t size_with_redzone; /* Size of the variable + size of the red zone. 32 bytes aligned */ >> + const void *name; >> + const void *module_name; /* Name of the module where the global variable is declared. */ >> + unsigned long has_dynamic_init; /* This needed for C++ */ > > This can be removed? > No, compiler dictates layout of this struct. That probably deserves a comment. >> +#if KASAN_ABI_VERSION >= 4 >> + struct kasan_source_location *location; >> +#endif >> +}; >> >> ... >> > > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org