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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_MUTT 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 04DCBC04AB1 for ; Thu, 9 May 2019 16:48:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B6828217D7 for ; Thu, 9 May 2019 16:48:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557420498; bh=kol39BephWYIHDzdaXrvumnDFI8vJt7AfTLmiFkdhCo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=Ntq7NrPsmQMBRaEEYdPwQAL2PzAdRbvFMG9//BzrhHJ1J4hMgc8fG9gzBfE4fpXIR piwcdlZoOt67c93Ljv84JJHBd2qROLqMsXEtnCwiGwWdN6ixvDR130LUPCmMmY5rLZ qQ+Oq3m73TQOToHMmc7CI8gZQEUqZ4IjwTIk888g= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726799AbfEIQsR (ORCPT ); Thu, 9 May 2019 12:48:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:57998 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726620AbfEIQsR (ORCPT ); Thu, 9 May 2019 12:48:17 -0400 Received: from localhost (unknown [104.132.1.68]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C38982177E; Thu, 9 May 2019 16:48:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557420495; bh=kol39BephWYIHDzdaXrvumnDFI8vJt7AfTLmiFkdhCo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WyoiZFRaABWrxW8LjQOdrsYbo/2yLzc26cJp0FY7SnFSbaquCK8BNIliPm64CIcp/ fhQcQ5ydKk9kI0oXGIyzVozzFiqDIGT/avn3QVPT254RRB4OwwtkbkVn4gXmVZPef3 TpTcLMRT8lHftvdnQJ7J5M+TKIFELZF53SS4CE7c= Date: Thu, 9 May 2019 09:48:14 -0700 From: Jaegeuk Kim To: Chao Yu Cc: Randall Huang , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5] f2fs: fix to avoid accessing xattr across the boundary Message-ID: <20190509164814.GA79912@jaegeuk-macbookpro.roam.corp.google.com> References: <20190411082646.169977-1-huangrandall@google.com> <20190509041535.GA62877@jaegeuk-macbookpro.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/09, Chao Yu wrote: > On 2019/5/9 12:15, Jaegeuk Kim wrote: > > On 04/11, Randall Huang wrote: > >> When we traverse xattr entries via __find_xattr(), > >> if the raw filesystem content is faked or any hardware failure occurs, > >> out-of-bound error can be detected by KASAN. > >> Fix the issue by introducing boundary check. > >> > >> [ 38.402878] c7 1827 BUG: KASAN: slab-out-of-bounds in f2fs_getxattr+0x518/0x68c > >> [ 38.402891] c7 1827 Read of size 4 at addr ffffffc0b6fb35dc by task > >> [ 38.402935] c7 1827 Call trace: > >> [ 38.402952] c7 1827 [] dump_backtrace+0x0/0x6bc > >> [ 38.402966] c7 1827 [] show_stack+0x20/0x2c > >> [ 38.402981] c7 1827 [] dump_stack+0xfc/0x140 > >> [ 38.402995] c7 1827 [] print_address_description+0x80/0x2d8 > >> [ 38.403009] c7 1827 [] kasan_report_error+0x198/0x1fc > >> [ 38.403022] c7 1827 [] kasan_report_error+0x0/0x1fc > >> [ 38.403037] c7 1827 [] __asan_load4+0x1b0/0x1b8 > >> [ 38.403051] c7 1827 [] f2fs_getxattr+0x518/0x68c > >> [ 38.403066] c7 1827 [] f2fs_xattr_generic_get+0xb0/0xd0 > >> [ 38.403080] c7 1827 [] __vfs_getxattr+0x1f4/0x1fc > >> [ 38.403096] c7 1827 [] inode_doinit_with_dentry+0x360/0x938 > >> [ 38.403109] c7 1827 [] selinux_d_instantiate+0x2c/0x38 > >> [ 38.403123] c7 1827 [] security_d_instantiate+0x68/0x98 > >> [ 38.403136] c7 1827 [] d_splice_alias+0x58/0x348 > >> [ 38.403149] c7 1827 [] f2fs_lookup+0x608/0x774 > >> [ 38.403163] c7 1827 [] lookup_slow+0x1e0/0x2cc > >> [ 38.403177] c7 1827 [] walk_component+0x160/0x520 > >> [ 38.403190] c7 1827 [] path_lookupat+0x110/0x2b4 > >> [ 38.403203] c7 1827 [] filename_lookup+0x1d8/0x3a8 > >> [ 38.403216] c7 1827 [] user_path_at_empty+0x54/0x68 > >> [ 38.403229] c7 1827 [] SyS_getxattr+0xb4/0x18c > >> [ 38.403241] c7 1827 [] el0_svc_naked+0x34/0x38 > >> > >> Bug: 126558260 > >> > >> Signed-off-by: Randall Huang > >> --- > >> v2: > >> * return EFAULT if OOB error is detected > >> > >> v3: > >> * fix typo in setxattr() > >> > >> v4: > >> * change boundry definition > >> > >> v5: > >> * revise boundry definition > >> --- > >> fs/f2fs/xattr.c | 32 +++++++++++++++++++++++++++----- > >> 1 file changed, 27 insertions(+), 5 deletions(-) > >> > >> diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c > >> index 848a785abe25..587429e29a69 100644 > >> --- a/fs/f2fs/xattr.c > >> +++ b/fs/f2fs/xattr.c > >> @@ -202,12 +202,18 @@ static inline const struct xattr_handler *f2fs_xattr_handler(int index) > >> return handler; > >> } > >> > >> -static struct f2fs_xattr_entry *__find_xattr(void *base_addr, int index, > >> - size_t len, const char *name) > >> +static struct f2fs_xattr_entry *__find_xattr(void *base_addr, > >> + void *last_base_addr, int index, > >> + size_t len, const char *name) > >> { > >> struct f2fs_xattr_entry *entry; > >> > >> list_for_each_xattr(entry, base_addr) { > >> + if ((void *)(entry) + sizeof(__u32) > last_base_addr || > >> + (void *)XATTR_NEXT_ENTRY(entry) + > >> + sizeof(__u32) > last_base_addr) > >> + return NULL; > >> + > >> if (entry->e_name_index != index) > >> continue; > >> if (entry->e_name_len != len) > >> @@ -298,6 +304,7 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage, > >> void **base_addr, int *base_size) > >> { > >> void *cur_addr, *txattr_addr, *last_addr = NULL; > >> + void *last_txattr_addr = NULL; > >> nid_t xnid = F2FS_I(inode)->i_xattr_nid; > >> unsigned int size = xnid ? VALID_XATTR_BLOCK_SIZE : 0; > >> unsigned int inline_size = inline_xattr_size(inode); > >> @@ -311,6 +318,8 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage, > >> if (!txattr_addr) > >> return -ENOMEM; > >> > >> + last_txattr_addr = (void *)txattr_addr + inline_size + size; > > > > I just found this should be + XATTR_PADDING_SIZE. Otherwise, generic/026 fails. > > Let me know, if there is any other concern below. > > We're trying to use [txattr_addr, last_txattr_addr] to indicate valid range of > xattr datas, any valid entries across the boundary is not allowed, so I think > it's correct to exclude padding space for last_txattr_addr. Okay, how about this? >From 2777e654371dd4207a3a7f4fb5fa39550053a080 Mon Sep 17 00:00:00 2001 From: Randall Huang Date: Thu, 11 Apr 2019 16:26:46 +0800 Subject: [PATCH] f2fs: fix to avoid accessing xattr across the boundary When we traverse xattr entries via __find_xattr(), if the raw filesystem content is faked or any hardware failure occurs, out-of-bound error can be detected by KASAN. Fix the issue by introducing boundary check. [ 38.402878] c7 1827 BUG: KASAN: slab-out-of-bounds in f2fs_getxattr+0x518/0x68c [ 38.402891] c7 1827 Read of size 4 at addr ffffffc0b6fb35dc by task [ 38.402935] c7 1827 Call trace: [ 38.402952] c7 1827 [] dump_backtrace+0x0/0x6bc [ 38.402966] c7 1827 [] show_stack+0x20/0x2c [ 38.402981] c7 1827 [] dump_stack+0xfc/0x140 [ 38.402995] c7 1827 [] print_address_description+0x80/0x2d8 [ 38.403009] c7 1827 [] kasan_report_error+0x198/0x1fc [ 38.403022] c7 1827 [] kasan_report_error+0x0/0x1fc [ 38.403037] c7 1827 [] __asan_load4+0x1b0/0x1b8 [ 38.403051] c7 1827 [] f2fs_getxattr+0x518/0x68c [ 38.403066] c7 1827 [] f2fs_xattr_generic_get+0xb0/0xd0 [ 38.403080] c7 1827 [] __vfs_getxattr+0x1f4/0x1fc [ 38.403096] c7 1827 [] inode_doinit_with_dentry+0x360/0x938 [ 38.403109] c7 1827 [] selinux_d_instantiate+0x2c/0x38 [ 38.403123] c7 1827 [] security_d_instantiate+0x68/0x98 [ 38.403136] c7 1827 [] d_splice_alias+0x58/0x348 [ 38.403149] c7 1827 [] f2fs_lookup+0x608/0x774 [ 38.403163] c7 1827 [] lookup_slow+0x1e0/0x2cc [ 38.403177] c7 1827 [] walk_component+0x160/0x520 [ 38.403190] c7 1827 [] path_lookupat+0x110/0x2b4 [ 38.403203] c7 1827 [] filename_lookup+0x1d8/0x3a8 [ 38.403216] c7 1827 [] user_path_at_empty+0x54/0x68 [ 38.403229] c7 1827 [] SyS_getxattr+0xb4/0x18c [ 38.403241] c7 1827 [] el0_svc_naked+0x34/0x38 Signed-off-by: Randall Huang [Jaegeuk Kim: Fix wrong ending boundary] Reviewed-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/xattr.c | 36 +++++++++++++++++++++++++++--------- fs/f2fs/xattr.h | 2 ++ 2 files changed, 29 insertions(+), 9 deletions(-) diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c index 848a785abe25..e791741d193b 100644 --- a/fs/f2fs/xattr.c +++ b/fs/f2fs/xattr.c @@ -202,12 +202,17 @@ static inline const struct xattr_handler *f2fs_xattr_handler(int index) return handler; } -static struct f2fs_xattr_entry *__find_xattr(void *base_addr, int index, - size_t len, const char *name) +static struct f2fs_xattr_entry *__find_xattr(void *base_addr, + void *last_base_addr, int index, + size_t len, const char *name) { struct f2fs_xattr_entry *entry; list_for_each_xattr(entry, base_addr) { + if ((void *)(entry) + sizeof(__u32) > last_base_addr || + (void *)XATTR_NEXT_ENTRY(entry) > last_base_addr) + return NULL; + if (entry->e_name_index != index) continue; if (entry->e_name_len != len) @@ -297,20 +302,22 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage, const char *name, struct f2fs_xattr_entry **xe, void **base_addr, int *base_size) { - void *cur_addr, *txattr_addr, *last_addr = NULL; + void *cur_addr, *txattr_addr, *last_txattr_addr; + void *last_addr = NULL; nid_t xnid = F2FS_I(inode)->i_xattr_nid; - unsigned int size = xnid ? VALID_XATTR_BLOCK_SIZE : 0; unsigned int inline_size = inline_xattr_size(inode); int err = 0; - if (!size && !inline_size) + if (!xnid && !inline_size) return -ENODATA; - *base_size = inline_size + size + XATTR_PADDING_SIZE; + *base_size = XATTR_SIZE(xnid, inode) + XATTR_PADDING_SIZE; txattr_addr = f2fs_kzalloc(F2FS_I_SB(inode), *base_size, GFP_NOFS); if (!txattr_addr) return -ENOMEM; + last_txattr_addr = (void *)txattr_addr + XATTR_SIZE(xnid, inode); + /* read from inline xattr */ if (inline_size) { err = read_inline_xattr(inode, ipage, txattr_addr); @@ -337,7 +344,11 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage, else cur_addr = txattr_addr; - *xe = __find_xattr(cur_addr, index, len, name); + *xe = __find_xattr(cur_addr, last_txattr_addr, index, len, name); + if (!*xe) { + err = -EFAULT; + goto out; + } check: if (IS_XATTR_LAST_ENTRY(*xe)) { err = -ENODATA; @@ -581,7 +592,8 @@ static int __f2fs_setxattr(struct inode *inode, int index, struct page *ipage, int flags) { struct f2fs_xattr_entry *here, *last; - void *base_addr; + void *base_addr, *last_base_addr; + nid_t xnid = F2FS_I(inode)->i_xattr_nid; int found, newsize; size_t len; __u32 new_hsize; @@ -605,8 +617,14 @@ static int __f2fs_setxattr(struct inode *inode, int index, if (error) return error; + last_base_addr = (void *)base_addr + XATTR_SIZE(xnid, inode); + /* find entry with wanted name. */ - here = __find_xattr(base_addr, index, len, name); + here = __find_xattr(base_addr, last_base_addr, index, len, name); + if (!here) { + error = -EFAULT; + goto exit; + } found = IS_XATTR_LAST_ENTRY(here) ? 0 : 1; diff --git a/fs/f2fs/xattr.h b/fs/f2fs/xattr.h index 9172ee082ca8..a90920e2f949 100644 --- a/fs/f2fs/xattr.h +++ b/fs/f2fs/xattr.h @@ -71,6 +71,8 @@ struct f2fs_xattr_entry { entry = XATTR_NEXT_ENTRY(entry)) #define VALID_XATTR_BLOCK_SIZE (PAGE_SIZE - sizeof(struct node_footer)) #define XATTR_PADDING_SIZE (sizeof(__u32)) +#define XATTR_SIZE(x,i) (((x) ? VALID_XATTR_BLOCK_SIZE : 0) + \ + (inline_xattr_size(i))) #define MIN_OFFSET(i) XATTR_ALIGN(inline_xattr_size(i) + \ VALID_XATTR_BLOCK_SIZE) -- 2.19.0.605.g01d371f741-goog