From patchwork Sun Nov 6 22:48:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 13033664 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 3963EC4321E for ; Sun, 6 Nov 2022 22:52:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230260AbiKFWwm (ORCPT ); Sun, 6 Nov 2022 17:52:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230036AbiKFWwi (ORCPT ); Sun, 6 Nov 2022 17:52:38 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A321C101E3; Sun, 6 Nov 2022 14:52:37 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 64DDBB80D37; Sun, 6 Nov 2022 22:52:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0400AC4347C; Sun, 6 Nov 2022 22:52:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667775155; bh=doSgKvL2ErW/F+kDQDJ3xeq4/JGRaB/+jqKEaI9++OA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jJTk58VK3XNftsorG1SUruxkPkcqMG3Y4FUCZ/dH+PVVl9XaNmoKxwIlo13UUTuaB tyY4PIRaihhJna0ylJ0BssqVapkOkoerbYk1vVGn4/nMRMY2lgVE/Fn8aYOVDO9G9I C5xTiYN80XbhWtN4ENjMtMFA8av39ztrEcSZ/NCD8J3kWSyd3h5gvtIS2Ph6xwep2Q A49ZR0RH/YV+yT4SSfy6g1EDiRgEGtsebANMQUy1GbJ+b4jo/+yE9ENxxPCUR3hlmQ 0r4rmyoVk7T2pRi4QCe5KyEEb/TDbabUJJIAN3HgbeZvSFzZ28r99O7blLTsuTaTKB lsn+/yggISAaQ== From: Eric Biggers To: linux-ext4@vger.kernel.org Cc: linux-fscrypt@vger.kernel.org, Harshad Shirwadkar , stable@vger.kernel.org Subject: [PATCH 5/7] ext4: fix unaligned memory access in ext4_fc_reserve_space() Date: Sun, 6 Nov 2022 14:48:39 -0800 Message-Id: <20221106224841.279231-6-ebiggers@kernel.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221106224841.279231-1-ebiggers@kernel.org> References: <20221106224841.279231-1-ebiggers@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org From: Eric Biggers As is done elsewhere in the file, build the struct ext4_fc_tl on the stack and memcpy() it into the buffer, rather than directly writing it to a potentially-unaligned location in the buffer. Fixes: aa75f4d3daae ("ext4: main fast-commit commit path") Cc: # v5.10+ Signed-off-by: Eric Biggers --- fs/ext4/fast_commit.c | 39 +++++++++++++++++++++------------------ 1 file changed, 21 insertions(+), 18 deletions(-) diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c index d5ad4b2b235d6..892fa7c7a768b 100644 --- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -675,6 +675,15 @@ static void ext4_fc_submit_bh(struct super_block *sb, bool is_tail) /* Ext4 commit path routines */ +/* memcpy to fc reserved space and update CRC */ +static void *ext4_fc_memcpy(struct super_block *sb, void *dst, const void *src, + int len, u32 *crc) +{ + if (crc) + *crc = ext4_chksum(EXT4_SB(sb), *crc, src, len); + return memcpy(dst, src, len); +} + /* memzero and update CRC */ static void *ext4_fc_memzero(struct super_block *sb, void *dst, int len, u32 *crc) @@ -700,12 +709,13 @@ static void *ext4_fc_memzero(struct super_block *sb, void *dst, int len, */ static u8 *ext4_fc_reserve_space(struct super_block *sb, int len, u32 *crc) { - struct ext4_fc_tl *tl; + struct ext4_fc_tl tl; struct ext4_sb_info *sbi = EXT4_SB(sb); struct buffer_head *bh; int bsize = sbi->s_journal->j_blocksize; int ret, off = sbi->s_fc_bytes % bsize; int pad_len; + u8 *dst; /* * After allocating len, we should have space at least for a 0 byte @@ -729,16 +739,18 @@ static u8 *ext4_fc_reserve_space(struct super_block *sb, int len, u32 *crc) return sbi->s_fc_bh->b_data + off; } /* Need to add PAD tag */ - tl = (struct ext4_fc_tl *)(sbi->s_fc_bh->b_data + off); - tl->fc_tag = cpu_to_le16(EXT4_FC_TAG_PAD); + dst = sbi->s_fc_bh->b_data + off; + tl.fc_tag = cpu_to_le16(EXT4_FC_TAG_PAD); pad_len = bsize - off - 1 - EXT4_FC_TAG_BASE_LEN; - tl->fc_len = cpu_to_le16(pad_len); - if (crc) - *crc = ext4_chksum(sbi, *crc, tl, EXT4_FC_TAG_BASE_LEN); - if (pad_len > 0) - ext4_fc_memzero(sb, tl + 1, pad_len, crc); + tl.fc_len = cpu_to_le16(pad_len); + ext4_fc_memcpy(sb, dst, &tl, EXT4_FC_TAG_BASE_LEN, crc); + dst += EXT4_FC_TAG_BASE_LEN; + if (pad_len > 0) { + ext4_fc_memzero(sb, dst, pad_len, crc); + dst += pad_len; + } /* Don't leak uninitialized memory in the unused last byte. */ - *((u8 *)(tl + 1) + pad_len) = 0; + *dst = 0; ext4_fc_submit_bh(sb, false); @@ -750,15 +762,6 @@ static u8 *ext4_fc_reserve_space(struct super_block *sb, int len, u32 *crc) return sbi->s_fc_bh->b_data; } -/* memcpy to fc reserved space and update CRC */ -static void *ext4_fc_memcpy(struct super_block *sb, void *dst, const void *src, - int len, u32 *crc) -{ - if (crc) - *crc = ext4_chksum(EXT4_SB(sb), *crc, src, len); - return memcpy(dst, src, len); -} - /* * Complete a fast commit by writing tail tag. *