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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id v11-20020a1709028d8b00b001cca8a01e68sm1840613plo.278.2023.11.30.12.51.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Nov 2023 12:51:21 -0800 (PST) From: Kees Cook To: Anders Larsen Cc: Kees Cook , Ronald Monthero , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2 1/2] qnx4: Extract dir entry filename processing into helper Date: Thu, 30 Nov 2023 12:51:18 -0800 Message-Id: <20231130205120.3642477-1-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231130205010.it.412-kees@kernel.org> References: <20231130205010.it.412-kees@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5530; i=keescook@chromium.org; h=from:subject; bh=DfWvLuw+1Lt1r34F/RNAIGyeJ3JO5Pv4v9kUKjoCgFA=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlaPXHlsbg/RAPaF3lRor/e48qn5raSb02XFsxv 4ZkTemLuR+JAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZWj1xwAKCRCJcvTf3G3A Ju2FD/9yVnVUO73divQnIWrfkfSj+m1SuNrgcl/i1pzadtaT1HTZsGUv+Ya3kGmHdGQ6fKVnWXi AJn7Pxt6bDSI6Pnp7WwFOPBb50LY7rDQD8VIVpPCShrBa8JeJ8rq6g8STu1qmTtxV7T1JuiacGt 1b2ANdJqcUJJ8cMf5NSaFV/FhgOcihqgxKmKg80oK/N777WPtUHKsO/8X0epDkYWno5tpOxB4K/ EiofZJ8k0RZESvH42dGmA42jq4x/AkPusFHZ6T7oI6+GtzcgcMT5c4Qlh2kMelzZgqSsnkL5yPa WtKaqrom/6134zXVgWqqhQHwg2JPvdnZCWCaPq5Kvy7ERMBDM0bNtU35mIueySSSRdxRF8C9O7W bB5/orMoswd6pf0ksFbpvpGU/F0cCYDEMt/5cH6iM4d6XDbNaEj+o2utREOzfvGRZkNGSvV3rhh byj83Bl55pNV48ZVFGPhRJYI0hqGWqq7b5ZQebP6Je0KZQ2+g6SjaXjCh5fD7PIZrSuwFPubmj9 zp9ooNGudzBGisaj/ruuw5Zuw9bvB+rBbgcFyeUPaLYijtn4kVy/lX+6+yj/LIOf746oaO7TqTd xbns0Al2CLsr5HmW2BYYaNJhz1/SOKSiVb6fHGk9ilzv6MsBmow/kOy0uae+UB39OCG1LcWHl1J KxbuPyxHqnqro3A== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Both dir.c and namei.c need to perform the same work to figure out a directory entry's name and size. Extract this into a helper for use in the next patch. Cc: Anders Larsen Link: https://lore.kernel.org/r/20231118033225.2181299-1-keescook@chromium.= org Signed-off-by: Kees Cook Acked-by: Anders Larsen --- fs/qnx4/dir.c | 52 ++++++------------------------------------- fs/qnx4/qnx4.h | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+), 45 deletions(-) diff --git a/fs/qnx4/dir.c b/fs/qnx4/dir.c index 66645a5a35f3..42a529e26bd6 100644 --- a/fs/qnx4/dir.c +++ b/fs/qnx4/dir.c @@ -15,43 +15,6 @@ #include #include "qnx4.h" =20 -/* - * A qnx4 directory entry is an inode entry or link info - * depending on the status field in the last byte. The - * first byte is where the name start either way, and a - * zero means it's empty. - * - * Also, due to a bug in gcc, we don't want to use the - * real (differently sized) name arrays in the inode and - * link entries, but always the 'de_name[]' one in the - * fake struct entry. - * - * See - * - * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99578#c6 - * - * for details, but basically gcc will take the size of the - * 'name' array from one of the used union entries randomly. - * - * This use of 'de_name[]' (48 bytes) avoids the false positive - * warnings that would happen if gcc decides to use 'inode.di_name' - * (16 bytes) even when the pointer and size were to come from - * 'link.dl_name' (48 bytes). - * - * In all cases the actual name pointer itself is the same, it's - * only the gcc internal 'what is the size of this field' logic - * that can get confused. - */ -union qnx4_directory_entry { - struct { - const char de_name[48]; - u8 de_pad[15]; - u8 de_status; - }; - struct qnx4_inode_entry inode; - struct qnx4_link_info link; -}; - static int qnx4_readdir(struct file *file, struct dir_context *ctx) { struct inode *inode =3D file_inode(file); @@ -74,26 +37,25 @@ static int qnx4_readdir(struct file *file, struct dir_c= ontext *ctx) ix =3D (ctx->pos >> QNX4_DIR_ENTRY_SIZE_BITS) % QNX4_INODES_PER_BLOCK; for (; ix < QNX4_INODES_PER_BLOCK; ix++, ctx->pos +=3D QNX4_DIR_ENTRY_SI= ZE) { union qnx4_directory_entry *de; + const char *fname; =20 offset =3D ix * QNX4_DIR_ENTRY_SIZE; de =3D (union qnx4_directory_entry *) (bh->b_data + offset); =20 - if (!de->de_name[0]) - continue; - if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK))) + fname =3D get_entry_fname(de, &size); + if (!fname) continue; + if (!(de->de_status & QNX4_FILE_LINK)) { - size =3D sizeof(de->inode.di_fname); ino =3D blknum * QNX4_INODES_PER_BLOCK + ix - 1; } else { - size =3D sizeof(de->link.dl_fname); ino =3D ( le32_to_cpu(de->link.dl_inode_blk) - 1 ) * QNX4_INODES_PER_BLOCK + de->link.dl_inode_ndx; } - size =3D strnlen(de->de_name, size); - QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, name)); - if (!dir_emit(ctx, de->de_name, size, ino, DT_UNKNOWN)) { + + QNX4DEBUG((KERN_INFO "qnx4_readdir:%.*s\n", size, fname)); + if (!dir_emit(ctx, fname, size, ino, DT_UNKNOWN)) { brelse(bh); return 0; } diff --git a/fs/qnx4/qnx4.h b/fs/qnx4/qnx4.h index 6283705466a4..5c2b1fb6b952 100644 --- a/fs/qnx4/qnx4.h +++ b/fs/qnx4/qnx4.h @@ -44,3 +44,63 @@ static inline struct qnx4_inode_entry *qnx4_raw_inode(st= ruct inode *inode) { return &qnx4_i(inode)->raw; } + +/* + * A qnx4 directory entry is an inode entry or link info + * depending on the status field in the last byte. The + * first byte is where the name start either way, and a + * zero means it's empty. + * + * Also, due to a bug in gcc, we don't want to use the + * real (differently sized) name arrays in the inode and + * link entries, but always the 'de_name[]' one in the + * fake struct entry. + * + * See + * + * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99578#c6 + * + * for details, but basically gcc will take the size of the + * 'name' array from one of the used union entries randomly. + * + * This use of 'de_name[]' (48 bytes) avoids the false positive + * warnings that would happen if gcc decides to use 'inode.di_name' + * (16 bytes) even when the pointer and size were to come from + * 'link.dl_name' (48 bytes). + * + * In all cases the actual name pointer itself is the same, it's + * only the gcc internal 'what is the size of this field' logic + * that can get confused. + */ +union qnx4_directory_entry { + struct { + const char de_name[48]; + u8 de_pad[15]; + u8 de_status; + }; + struct qnx4_inode_entry inode; + struct qnx4_link_info link; +}; + +static inline const char *get_entry_fname(union qnx4_directory_entry *de, + int *size) +{ + /* Make sure the status byte is in the same place for all structs. */ + BUILD_BUG_ON(offsetof(struct qnx4_inode_entry, di_status) !=3D + offsetof(struct qnx4_link_info, dl_status)); + BUILD_BUG_ON(offsetof(struct qnx4_inode_entry, di_status) !=3D + offsetof(union qnx4_directory_entry, de_status)); + + if (!de->de_name[0]) + return NULL; + if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK))) + return NULL; + if (!(de->de_status & QNX4_FILE_LINK)) + *size =3D sizeof(de->inode.di_fname); + else + *size =3D sizeof(de->link.dl_fname); + + *size =3D strnlen(de->de_name, *size); + + return de->de_name; +} --=20 2.34.1 From nobody Tue Dec 16 16:35:17 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9B4F9C07CA9 for ; Thu, 30 Nov 2023 20:51:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376798AbjK3UvX (ORCPT ); Thu, 30 Nov 2023 15:51:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1376740AbjK3UvQ (ORCPT ); Thu, 30 Nov 2023 15:51:16 -0500 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D70211713 for ; Thu, 30 Nov 2023 12:51:22 -0800 (PST) Received: by mail-pf1-x436.google.com with SMTP id d2e1a72fcca58-6cdfb721824so195262b3a.3 for ; Thu, 30 Nov 2023 12:51:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1701377482; x=1701982282; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=JHspbjyNxD70S26h5FJFbJyrOIpjQKEiRZEPO/RowOY=; b=YQxvOw0t1CbnlpsR46OUOms4DEPmzvsbiw1fyX8MpNED6y7LWiQ9FvJfTa6w0B4QEc MT2RAgXiah5yqVm3BQenT6T+rO2QVnz6Av0xSzPk/bkBRDK21QTd47fogsBd52a6ie67 WUXlZ7M8p/8gSRXf3/bOdZe5yjqpZhxq5UZww= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701377482; x=1701982282; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=JHspbjyNxD70S26h5FJFbJyrOIpjQKEiRZEPO/RowOY=; b=dktjPwjQMnuW0TLqx8twRHeb/iR7RCjNsyK+wta8jTdgDx8VQR0PY2U61e1QxGMQ1y uxJQAdMo7sKDZFTj17wb6TvYYl0V1AlUa2nxB/a8rThoSbx6vXOITACDb9/HccweXsQN YihtbfJtppxIG744+QFy3ErVmpiPpHAP5xlCqXREyjBS/+zFLhXcUJ9oXsoDMFUwabjz o17p9uTNQDkyNkHJrjv6F0FUaNiiXF/PnZT+2b4osWLKL2GKU/26luVqKud3GnTa4cDs qkRJHDclaiPAV/rlJiWm0NNnxxSSRNnSKqWp6KOdX9FSdu6XClyKkhhUPfuHOPcPrpUe z1fg== X-Gm-Message-State: AOJu0Ywd5XbcQG366vz6zy3m69M7nO730JpdJ8j0YjmWPQDhvacUTagd icuPfdzerGVG+Z9be4N5mLMkxw== X-Google-Smtp-Source: AGHT+IFm/DuSKcpDXL4yPGVmvfLKtyAbGASsT7oxedviVQc3mYSpRkK8dKsCbVIVi7NEegnOzk/qHA== X-Received: by 2002:a05:6a00:6c86:b0:6cd:d8c6:5f2d with SMTP id jc6-20020a056a006c8600b006cdd8c65f2dmr7397977pfb.2.1701377482345; Thu, 30 Nov 2023 12:51:22 -0800 (PST) Received: from www.outflux.net (198-0-35-241-static.hfc.comcastbusiness.net. [198.0.35.241]) by smtp.gmail.com with ESMTPSA id e23-20020a63d957000000b005b7dd356f75sm1707007pgj.32.2023.11.30.12.51.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Nov 2023 12:51:21 -0800 (PST) From: Kees Cook To: Anders Larsen Cc: Kees Cook , Ronald Monthero , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2 2/2] qnx4: Use get_directory_fname() in qnx4_match() Date: Thu, 30 Nov 2023 12:51:19 -0800 Message-Id: <20231130205120.3642477-2-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231130205010.it.412-kees@kernel.org> References: <20231130205010.it.412-kees@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2137; i=keescook@chromium.org; h=from:subject; bh=0NRaB2XyKTke+LAIiZpTjtyDvsns87ckz1A+4wFT/pU=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlaPXHwMRifvoP3X5IR1swGuZKu3ezjNx6+q9Y/ rued3z2/QSJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZWj1xwAKCRCJcvTf3G3A JrG9D/9U5Pt6Io0TBKu5fsoHGeADe3EEyPVr7dNlaSkT0fd+Z/wUv4HjAeK18w8+mEqzKmc+8D7 osq79lqROKhvGAzuGte+1dtUAJyrG2N+kIY7whVWjFYj4aJe9hMLi0E+gHz2F8BvYdqHQqgU2s+ qZX0/u3GMTF27uOLRvWKgGkvf1quTpALZEm0jbwf9lRMIYHUdmtXP8IRCYnkM+4QNUktyAK4Krb Dy/Ievfz1/oZbltim3dvynxT4mW/gVzLy6wYEuIIR4869XRwaMNR30r7Ed+qcL0DkTrB4OtcRNa qyYp1GGNlvQwKN0EfJiYldys+16liBo7iFSaocEeeHxl/4Oic1xjF40gIWQQgrdzvafhAF+Ojkc t17iCMyooYWMfhjsmQHwg4LK2UPHKYN/o436ElHiNmfm6dI+/R2umxX52SUKIgIzKX9+pEM78HK j26HLelWfEjfBzhhLYlSGeVX+KX5vzfIBoLjdhIurCLq4Sv3M7NvCGgJzINZsuyYDI1VTxoEbi3 QihxHdAviQUn4QrllwBAW3JPmFaBxWIgQ44D9E8jfW0pJ94L/ClDxU47yv0ocYxzAVbNn7BRM6o U3sm5w5geeMVlifVE2Kn31bRC4LL4Y3P5edIn4YqZ8kUuHvZKG1pYSn4Vt/3wmFM4SQGpP9AOtM O5YgvLYssasy3wA== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Use the new common directory entry name accessor helper to avoid confusing the compiler about over-running the file name buffer. Avoids false positive buffer overflow warning: [ 4849.636861] detected buffer overflow in strlen [ 4849.636897] ------------[ cut here ]------------ [ 4849.636902] kernel BUG at lib/string.c:1165! ... [ 4849.637047] Call Trace: ... [ 4849.637251] qnx4_find_entry.cold+0xc/0x18 [qnx4] [ 4849.637264] qnx4_lookup+0x3c/0xa0 [qnx4] Cc: Anders Larsen Reported-by: Ronald Monthero Closes: https://lore.kernel.org/lkml/20231112095353.579855-1-debug.penguin3= 2@gmail.com/ Link: https://lore.kernel.org/r/20231118033225.2181299-2-keescook@chromium.= org Signed-off-by: Kees Cook Acked-by: Anders Larsen --- fs/qnx4/namei.c | 29 +++++++++++------------------ 1 file changed, 11 insertions(+), 18 deletions(-) diff --git a/fs/qnx4/namei.c b/fs/qnx4/namei.c index 8d72221735d7..bb8db6550ca5 100644 --- a/fs/qnx4/namei.c +++ b/fs/qnx4/namei.c @@ -26,31 +26,24 @@ static int qnx4_match(int len, const char *name, struct buffer_head *bh, unsigned long *offset) { - struct qnx4_inode_entry *de; - int namelen, thislen; + union qnx4_directory_entry *de; + const char *fname; + int fnamelen; =20 if (bh =3D=3D NULL) { printk(KERN_WARNING "qnx4: matching unassigned buffer !\n"); return 0; } - de =3D (struct qnx4_inode_entry *) (bh->b_data + *offset); + de =3D (union qnx4_directory_entry *) (bh->b_data + *offset); *offset +=3D QNX4_DIR_ENTRY_SIZE; - if ((de->di_status & QNX4_FILE_LINK) !=3D 0) { - namelen =3D QNX4_NAME_MAX; - } else { - namelen =3D QNX4_SHORT_NAME_MAX; - } - thislen =3D strlen( de->di_fname ); - if ( thislen > namelen ) - thislen =3D namelen; - if (len !=3D thislen) { + + fname =3D get_entry_fname(de, &fnamelen); + if (!fname || len !=3D fnamelen) return 0; - } - if (strncmp(name, de->di_fname, len) =3D=3D 0) { - if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) !=3D 0) { - return 1; - } - } + + if (strncmp(name, fname, len) =3D=3D 0) + return 1; + return 0; } =20 --=20 2.34.1