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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 DA998C433DF for ; Mon, 1 Jun 2020 20:08:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B7B4A207DF for ; Mon, 1 Jun 2020 20:08:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591042116; bh=85zG2AyYa1iBuFIil+uEjS+WxblsLLJ2fCz4UIcuvB0=; h=From:To:Cc:Subject:Date:List-ID:From; b=uqW7ps5fQviCFIGwTbimzZGXWcFDgk1H8K1mkTbrAUpNTbrBQJv5A+f65WLoqPdO0 6shDfzhB6Gm6G0/U8NnqJuIsxV8G436/aY7Y5zVJ+eAodr2HgaTGHGKqqakPQdTQ/5 qFkqk4k0XBhXLr2Moswd6Kk6LdQc7fs2xB7OlfIo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728350AbgFAUIf (ORCPT ); Mon, 1 Jun 2020 16:08:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:46552 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726201AbgFAUIf (ORCPT ); Mon, 1 Jun 2020 16:08:35 -0400 Received: from sol.hsd1.ca.comcast.net (c-107-3-166-239.hsd1.ca.comcast.net [107.3.166.239]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D119E20734; Mon, 1 Jun 2020 20:08:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591042115; bh=85zG2AyYa1iBuFIil+uEjS+WxblsLLJ2fCz4UIcuvB0=; h=From:To:Cc:Subject:Date:From; b=bWKFmytTENc3vIROh8oQVWS1O0w1comVKM+t+gE9ks8imExM5DT6P5bLl2uv+8F+H kmKMJK+ltnLXxYGFjA24VPmHpyD6aZeUlxiqtthaluyVGj9zT+YnYHpP8gR62W6Q4a t3oNWPVc1HbbNM3uvgCrfqsnhMQ48ZHYrh1mJSXE= From: Eric Biggers To: linux-f2fs-devel@lists.sourceforge.net Cc: linux-ext4@vger.kernel.org, Daniel Rosenberg , stable@vger.kernel.org, Al Viro , linux-fsdevel@vger.kernel.org, Gabriel Krisman Bertazi Subject: [PATCH v2] f2fs: avoid utf8_strncasecmp() with unstable name Date: Mon, 1 Jun 2020 13:08:05 -0700 Message-Id: <20200601200805.59655-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org From: Eric Biggers If the dentry name passed to ->d_compare() fits in dentry::d_iname, then it may be concurrently modified by a rename. This can cause undefined behavior (possibly out-of-bounds memory accesses or crashes) in utf8_strncasecmp(), since fs/unicode/ isn't written to handle strings that may be concurrently modified. Fix this by first copying the filename to a stack buffer if needed. This way we get a stable snapshot of the filename. Fixes: 2c2eb7a300cd ("f2fs: Support case-insensitive file name lookups") Cc: # v5.4+ Cc: Al Viro Cc: Daniel Rosenberg Cc: Gabriel Krisman Bertazi Signed-off-by: Eric Biggers --- v2: Use memcpy() + barrier() instead of a byte-by-byte copy. Also rebased onto f2fs/dev. fs/f2fs/dir.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c index 29f70f2295cce..d35976785e8c5 100644 --- a/fs/f2fs/dir.c +++ b/fs/f2fs/dir.c @@ -1114,11 +1114,27 @@ static int f2fs_d_compare(const struct dentry *dentry, unsigned int len, const struct inode *dir = READ_ONCE(parent->d_inode); const struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb); struct qstr entry = QSTR_INIT(str, len); + char strbuf[DNAME_INLINE_LEN]; int res; if (!dir || !IS_CASEFOLDED(dir)) goto fallback; + /* + * If the dentry name is stored in-line, then it may be concurrently + * modified by a rename. If this happens, the VFS will eventually retry + * the lookup, so it doesn't matter what ->d_compare() returns. + * However, it's unsafe to call utf8_strncasecmp() with an unstable + * string. Therefore, we have to copy the name into a temporary buffer. + */ + if (len <= DNAME_INLINE_LEN - 1) { + memcpy(strbuf, str, len); + strbuf[len] = 0; + entry.name = strbuf; + /* prevent compiler from optimizing out the temporary buffer */ + barrier(); + } + res = utf8_strncasecmp(sbi->s_encoding, name, &entry); if (res >= 0) return res; -- 2.26.2 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=-9.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 08BA7C433DF for ; Mon, 1 Jun 2020 20:08:54 +0000 (UTC) Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CBE2A2074B; 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bh=y3/uOANY7bMTo2oq9mZzLCRTKxdM2HUGMbWcQAsGPY8=; b=Q T89p7f6H40Dq8KGghwZY/tqn3T1IOWiM80iTSwLy6Dpg2O+oQlu1VqhAHfqFDtgHuJT3pIiUp97Th TVZllA9Um6pYPq14cGWCA7CUdW03nG2twqodd6cjGet2lqdQ9eh/IQjf3ss9ymp3v7NbynV9ZhHV5 fQl2lPdgZC4cd0yU=; Received: from mail.kernel.org ([198.145.29.99]) by sfi-mx-3.v28.lw.sourceforge.com with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.92.2) id 1jfqjn-004kmq-Ls for linux-f2fs-devel@lists.sourceforge.net; Mon, 01 Jun 2020 20:08:51 +0000 Received: from sol.hsd1.ca.comcast.net (c-107-3-166-239.hsd1.ca.comcast.net [107.3.166.239]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D119E20734; Mon, 1 Jun 2020 20:08:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591042115; bh=85zG2AyYa1iBuFIil+uEjS+WxblsLLJ2fCz4UIcuvB0=; h=From:To:Cc:Subject:Date:From; b=bWKFmytTENc3vIROh8oQVWS1O0w1comVKM+t+gE9ks8imExM5DT6P5bLl2uv+8F+H kmKMJK+ltnLXxYGFjA24VPmHpyD6aZeUlxiqtthaluyVGj9zT+YnYHpP8gR62W6Q4a t3oNWPVc1HbbNM3uvgCrfqsnhMQ48ZHYrh1mJSXE= From: Eric Biggers To: linux-f2fs-devel@lists.sourceforge.net Date: Mon, 1 Jun 2020 13:08:05 -0700 Message-Id: <20200601200805.59655-1-ebiggers@kernel.org> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 X-Headers-End: 1jfqjn-004kmq-Ls Subject: [f2fs-dev] [PATCH v2] f2fs: avoid utf8_strncasecmp() with unstable name X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Daniel Rosenberg , stable@vger.kernel.org, Al Viro , linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Gabriel Krisman Bertazi Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net From: Eric Biggers If the dentry name passed to ->d_compare() fits in dentry::d_iname, then it may be concurrently modified by a rename. This can cause undefined behavior (possibly out-of-bounds memory accesses or crashes) in utf8_strncasecmp(), since fs/unicode/ isn't written to handle strings that may be concurrently modified. Fix this by first copying the filename to a stack buffer if needed. This way we get a stable snapshot of the filename. Fixes: 2c2eb7a300cd ("f2fs: Support case-insensitive file name lookups") Cc: # v5.4+ Cc: Al Viro Cc: Daniel Rosenberg Cc: Gabriel Krisman Bertazi Signed-off-by: Eric Biggers --- v2: Use memcpy() + barrier() instead of a byte-by-byte copy. Also rebased onto f2fs/dev. fs/f2fs/dir.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c index 29f70f2295cce..d35976785e8c5 100644 --- a/fs/f2fs/dir.c +++ b/fs/f2fs/dir.c @@ -1114,11 +1114,27 @@ static int f2fs_d_compare(const struct dentry *dentry, unsigned int len, const struct inode *dir = READ_ONCE(parent->d_inode); const struct f2fs_sb_info *sbi = F2FS_SB(dentry->d_sb); struct qstr entry = QSTR_INIT(str, len); + char strbuf[DNAME_INLINE_LEN]; int res; if (!dir || !IS_CASEFOLDED(dir)) goto fallback; + /* + * If the dentry name is stored in-line, then it may be concurrently + * modified by a rename. If this happens, the VFS will eventually retry + * the lookup, so it doesn't matter what ->d_compare() returns. + * However, it's unsafe to call utf8_strncasecmp() with an unstable + * string. Therefore, we have to copy the name into a temporary buffer. + */ + if (len <= DNAME_INLINE_LEN - 1) { + memcpy(strbuf, str, len); + strbuf[len] = 0; + entry.name = strbuf; + /* prevent compiler from optimizing out the temporary buffer */ + barrier(); + } + res = utf8_strncasecmp(sbi->s_encoding, name, &entry); if (res >= 0) return res; -- 2.26.2 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel