From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7334C04AB4 for ; Tue, 21 May 2019 15:43:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A5CFD208C3 for ; Tue, 21 May 2019 15:43:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728816AbfEUPnn (ORCPT ); Tue, 21 May 2019 11:43:43 -0400 Received: from relay.sw.ru ([185.231.240.75]:37486 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727941AbfEUPnn (ORCPT ); Tue, 21 May 2019 11:43:43 -0400 Received: from [172.16.25.12] by relay.sw.ru with esmtp (Exim 4.91) (envelope-from ) id 1hT6vS-00073c-UC; Tue, 21 May 2019 18:43:39 +0300 Subject: Re: [PATCH v2] mm/kasan: Print frame description for stack bugs To: Marco Elver , dvyukov@google.com, glider@google.com, andreyknvl@google.com, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com References: <20190520154751.84763-1-elver@google.com> From: Andrey Ryabinin Message-ID: Date: Tue, 21 May 2019 18:43:54 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190520154751.84763-1-elver@google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/20/19 6:47 PM, Marco Elver wrote: > +static void print_decoded_frame_descr(const char *frame_descr) > +{ > + /* > + * We need to parse the following string: > + * "n alloc_1 alloc_2 ... alloc_n" > + * where alloc_i looks like > + * "offset size len name" > + * or "offset size len name:line". > + */ > + > + char token[64]; > + unsigned long num_objects; > + > + if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > + &num_objects)) > + return; > + > + pr_err("\n"); > + pr_err("this frame has %lu %s:\n", num_objects, > + num_objects == 1 ? "object" : "objects"); > + > + while (num_objects--) { > + unsigned long offset; > + unsigned long size; > + > + /* access offset */ > + if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > + &offset)) > + return; > + /* access size */ > + if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > + &size)) > + return; > + /* name length (unused) */ > + if (!tokenize_frame_descr(&frame_descr, NULL, 0, NULL)) > + return; > + /* object name */ > + if (!tokenize_frame_descr(&frame_descr, token, sizeof(token), > + NULL)) > + return; > + > + /* Strip line number, if it exists. */ Why? > + strreplace(token, ':', '\0'); > + ... > + > + aligned_addr = round_down((unsigned long)addr, sizeof(long)); > + mem_ptr = round_down(aligned_addr, KASAN_SHADOW_SCALE_SIZE); > + shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr); > + shadow_bottom = kasan_mem_to_shadow(end_of_stack(current)); > + > + while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) { > + shadow_ptr--; > + mem_ptr -= KASAN_SHADOW_SCALE_SIZE; > + } > + > + while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) { > + shadow_ptr--; > + mem_ptr -= KASAN_SHADOW_SCALE_SIZE; > + } > + I suppose this won't work if stack grows up, which is fine because it grows up only on parisc arch. But "BUILD_BUG_ON(IS_ENABLED(CONFIG_STACK_GROUWSUP))" somewhere wouldn't hurt.