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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 92966C43460 for ; Fri, 7 May 2021 01:06:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7499D613CD for ; Fri, 7 May 2021 01:06:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231268AbhEGBHJ (ORCPT ); Thu, 6 May 2021 21:07:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:48776 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230444AbhEGBHJ (ORCPT ); Thu, 6 May 2021 21:07:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 086A0613C9; Fri, 7 May 2021 01:06:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1620349570; bh=h5xWlw++/J4KekLzEuGg8WbQkHU2W0pu3hpoaSnOsMI=; h=Date:From:To:Subject:In-Reply-To:From; b=uzO6wtt1Bm/SKdmnEPF/ccl9MHUC7yjqCStteFEh/zcZ2OpHF6g1qe/RjZTHMgYrT t1vZFZGkqwMcFD7OY4eY5PyOc/K9BYJuXyrRsf3GNrfr8h5cza097iWW7LzYYMynBo GOgv6TgyNNdirkfhEDDYOPLLtAlQua6adkG0qNjA= Date: Thu, 06 May 2021 18:06:09 -0700 From: Andrew Morton To: 0x7f454c46@gmail.com, akpm@linux-foundation.org, cl@linux.com, iamjoonsoo.kim@lge.com, linux-mm@kvack.org, linux@armlinux.org.uk, maninder1.s@samsung.com, mm-commits@vger.kernel.org, paulmck@kernel.org, penberg@kernel.org, rientjes@google.com, torvalds@linux-foundation.org, v.narang@samsung.com, vbabka@suse.cz, viro@zeniv.linux.org.uk Subject: [patch 77/91] arm: print alloc free paths for address in registers Message-ID: <20210507010609.arjStHN5i%akpm@linux-foundation.org> In-Reply-To: <20210506180126.03e1baee7ca52bedb6cc6003@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Maninder Singh Subject: arm: print alloc free paths for address in registers In case of a use after free kernel oops, the freeing path of the object is required to debug futher. In most of cases the object address is present in one of the registers. Thus check the register's address and if it belongs to slab, print its alloc and free path. e.g. in the below issue register r6 belongs to slab, and a use after free issue occurred on one of its dereferenced values: [ 20.182197] Unable to handle kernel paging request at virtual address 6b6b6b6f .... [ 20.185035] pc : [] lr : [] psr: 60000013 [ 20.185271] sp : c8927d40 ip : ffffefff fp : c8aa8020 [ 20.185462] r10: c8927e10 r9 : 00000001 r8 : 00400cc0 [ 20.185674] r7 : 00000000 r6 : c8ab0180 r5 : c1804a80 r4 : c8aa8008 [ 20.185924] r3 : c1a5661c r2 : 00000000 r1 : 6b6b6b6b r0 : c139bf48 ..... [ 20.191499] Register r6 information: slab kmalloc-64 start c8ab0140 data offset 64 pointer offset 0 size 64 allocated at meminfo_proc_show+0x40/0x4fc [ 20.192078] meminfo_proc_show+0x40/0x4fc [ 20.192263] seq_read_iter+0x18c/0x4c4 [ 20.192430] proc_reg_read_iter+0x84/0xac [ 20.192617] generic_file_splice_read+0xe8/0x17c [ 20.192816] splice_direct_to_actor+0xb8/0x290 [ 20.193008] do_splice_direct+0xa0/0xe0 [ 20.193185] do_sendfile+0x2d0/0x438 [ 20.193345] sys_sendfile64+0x12c/0x140 [ 20.193523] ret_fast_syscall+0x0/0x58 [ 20.193695] 0xbeeacde4 [ 20.193822] Free path: [ 20.193935] meminfo_proc_show+0x5c/0x4fc [ 20.194115] seq_read_iter+0x18c/0x4c4 [ 20.194285] proc_reg_read_iter+0x84/0xac [ 20.194475] generic_file_splice_read+0xe8/0x17c [ 20.194685] splice_direct_to_actor+0xb8/0x290 [ 20.194870] do_splice_direct+0xa0/0xe0 [ 20.195014] do_sendfile+0x2d0/0x438 [ 20.195174] sys_sendfile64+0x12c/0x140 [ 20.195336] ret_fast_syscall+0x0/0x58 [ 20.195491] 0xbeeacde4 Link: https://lkml.kernel.org/r/1615891032-29160-3-git-send-email-maninder1.s@samsung.com Co-developed-by: Vaneet Narang Signed-off-by: Vaneet Narang Signed-off-by: Maninder Singh Cc: Al Viro Cc: Christoph Lameter Cc: David Rientjes Cc: Dmitry Safonov <0x7f454c46@gmail.com> Cc: Joonsoo Kim Cc: Paul E. McKenney Cc: Pekka Enberg Cc: Russell King Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- arch/arm/include/asm/bug.h | 1 + arch/arm/kernel/process.c | 11 +++++++++++ arch/arm/kernel/traps.c | 1 + 3 files changed, 13 insertions(+) --- a/arch/arm/include/asm/bug.h~arm-print-alloc-free-paths-for-address-in-registers +++ a/arch/arm/include/asm/bug.h @@ -88,5 +88,6 @@ extern asmlinkage void c_backtrace(unsig struct mm_struct; void show_pte(const char *lvl, struct mm_struct *mm, unsigned long addr); extern void __show_regs(struct pt_regs *); +extern void __show_regs_alloc_free(struct pt_regs *regs); #endif --- a/arch/arm/kernel/process.c~arm-print-alloc-free-paths-for-address-in-registers +++ a/arch/arm/kernel/process.c @@ -92,6 +92,17 @@ void arch_cpu_idle_exit(void) ledtrig_cpu(CPU_LED_IDLE_END); } +void __show_regs_alloc_free(struct pt_regs *regs) +{ + int i; + + /* check for r0 - r12 only */ + for (i = 0; i < 13; i++) { + pr_alert("Register r%d information:", i); + mem_dump_obj((void *)regs->uregs[i]); + } +} + void __show_regs(struct pt_regs *regs) { unsigned long flags; --- a/arch/arm/kernel/traps.c~arm-print-alloc-free-paths-for-address-in-registers +++ a/arch/arm/kernel/traps.c @@ -287,6 +287,7 @@ static int __die(const char *str, int er print_modules(); __show_regs(regs); + __show_regs_alloc_free(regs); pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n", TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk)); _