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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 946C4C4708E for ; Wed, 4 Jan 2023 16:29:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239925AbjADQ3M (ORCPT ); Wed, 4 Jan 2023 11:29:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51384 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239883AbjADQ2k (ORCPT ); Wed, 4 Jan 2023 11:28:40 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3318A3FCB1 for ; Wed, 4 Jan 2023 08:27:58 -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 C9150B817B7 for ; Wed, 4 Jan 2023 16:27:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B8B9C433D2; Wed, 4 Jan 2023 16:27:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672849675; bh=Cb6iu7EEQeR1fXuOpokNgHFvrMoE+ZBJMMjZ4GMiksw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GIZtCl+uqE15a81BiiYBO3kXZg6q2xE+hcTcBZ/cdN4dVwt6VE73+WmuHXTKntFmc 7RU3Z3/C7l5r3ClFuNvlmApylaCIpSsF2PGnvtSGTkBG7J1+ESVu/kS78HuhtIdLeW dmHeKUfxWHraQ1+pN0DvY0I1bIyyeX2TyQc34e1k= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Biggers , Theodore Tso Subject: [PATCH 6.0 151/177] ext4: fix off-by-one errors in fast-commit block filling Date: Wed, 4 Jan 2023 17:07:22 +0100 Message-Id: <20230104160512.236076281@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230104160507.635888536@linuxfoundation.org> References: <20230104160507.635888536@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Biggers commit 48a6a66db82b8043d298a630f22c62d43550cae5 upstream. Due to several different off-by-one errors, or perhaps due to a late change in design that wasn't fully reflected in the code that was actually merged, there are several very strange constraints on how fast-commit blocks are filled with tlv entries: - tlvs must start at least 10 bytes before the end of the block, even though the minimum tlv length is 8. Otherwise, the replay code will ignore them. (BUG: ext4_fc_reserve_space() could violate this requirement if called with a len of blocksize - 9 or blocksize - 8. Fortunately, this doesn't seem to happen currently.) - tlvs must end at least 1 byte before the end of the block. Otherwise the replay code will consider them to be invalid. This quirk contributed to a bug (fixed by an earlier commit) where uninitialized memory was being leaked to disk in the last byte of blocks. Also, strangely these constraints don't apply to the replay code in e2fsprogs, which will accept any tlvs in the blocks (with no bounds checks at all, but that is a separate issue...). Given that this all seems to be a bug, let's fix it by just filling blocks with tlv entries in the natural way. Note that old kernels will be unable to replay fast-commit journals created by kernels that have this commit. Fixes: aa75f4d3daae ("ext4: main fast-commit commit path") Cc: # v5.10+ Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20221106224841.279231-7-ebiggers@kernel.org Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/fast_commit.c | 66 +++++++++++++++++++++++++------------------------- 1 file changed, 33 insertions(+), 33 deletions(-) --- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -722,43 +722,43 @@ static u8 *ext4_fc_reserve_space(struct struct buffer_head *bh; int bsize = sbi->s_journal->j_blocksize; int ret, off = sbi->s_fc_bytes % bsize; - int pad_len; + int remaining; u8 *dst; /* - * After allocating len, we should have space at least for a 0 byte - * padding. + * If 'len' is too long to fit in any block alongside a PAD tlv, then we + * cannot fulfill the request. */ - if (len + EXT4_FC_TAG_BASE_LEN > bsize) + if (len > bsize - EXT4_FC_TAG_BASE_LEN) return NULL; - if (bsize - off - 1 > len + EXT4_FC_TAG_BASE_LEN) { - /* - * Only allocate from current buffer if we have enough space for - * this request AND we have space to add a zero byte padding. - */ - if (!sbi->s_fc_bh) { - ret = jbd2_fc_get_buf(EXT4_SB(sb)->s_journal, &bh); - if (ret) - return NULL; - sbi->s_fc_bh = bh; - } - sbi->s_fc_bytes += len; - return sbi->s_fc_bh->b_data + off; + if (!sbi->s_fc_bh) { + ret = jbd2_fc_get_buf(EXT4_SB(sb)->s_journal, &bh); + if (ret) + return NULL; + sbi->s_fc_bh = bh; } - /* Need to add PAD tag */ dst = sbi->s_fc_bh->b_data + off; + + /* + * Allocate the bytes in the current block if we can do so while still + * leaving enough space for a PAD tlv. + */ + remaining = bsize - EXT4_FC_TAG_BASE_LEN - off; + if (len <= remaining) { + sbi->s_fc_bytes += len; + return dst; + } + + /* + * Else, terminate the current block with a PAD tlv, then allocate a new + * block and allocate the bytes at the start of that new block. + */ + 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); + tl.fc_len = cpu_to_le16(remaining); 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. */ - *dst = 0; + ext4_fc_memzero(sb, dst + EXT4_FC_TAG_BASE_LEN, remaining, crc); ext4_fc_submit_bh(sb, false); @@ -766,7 +766,7 @@ static u8 *ext4_fc_reserve_space(struct if (ret) return NULL; sbi->s_fc_bh = bh; - sbi->s_fc_bytes = (sbi->s_fc_bytes / bsize + 1) * bsize + len; + sbi->s_fc_bytes += bsize - off + len; return sbi->s_fc_bh->b_data; } @@ -797,7 +797,7 @@ static int ext4_fc_write_tail(struct sup off = sbi->s_fc_bytes % bsize; tl.fc_tag = cpu_to_le16(EXT4_FC_TAG_TAIL); - tl.fc_len = cpu_to_le16(bsize - off - 1 + sizeof(struct ext4_fc_tail)); + tl.fc_len = cpu_to_le16(bsize - off + sizeof(struct ext4_fc_tail)); sbi->s_fc_bytes = round_up(sbi->s_fc_bytes, bsize); ext4_fc_memcpy(sb, dst, &tl, EXT4_FC_TAG_BASE_LEN, &crc); @@ -2065,7 +2065,7 @@ static int ext4_fc_replay_scan(journal_t state = &sbi->s_fc_replay_state; start = (u8 *)bh->b_data; - end = (__u8 *)bh->b_data + journal->j_blocksize - 1; + end = start + journal->j_blocksize; if (state->fc_replay_expected_off == 0) { state->fc_cur_tag = 0; @@ -2086,7 +2086,7 @@ static int ext4_fc_replay_scan(journal_t } state->fc_replay_expected_off++; - for (cur = start; cur < end - EXT4_FC_TAG_BASE_LEN; + for (cur = start; cur <= end - EXT4_FC_TAG_BASE_LEN; cur = cur + EXT4_FC_TAG_BASE_LEN + tl.fc_len) { ext4_fc_get_tl(&tl, cur); val = cur + EXT4_FC_TAG_BASE_LEN; @@ -2204,9 +2204,9 @@ static int ext4_fc_replay(journal_t *jou #endif start = (u8 *)bh->b_data; - end = (__u8 *)bh->b_data + journal->j_blocksize - 1; + end = start + journal->j_blocksize; - for (cur = start; cur < end - EXT4_FC_TAG_BASE_LEN; + for (cur = start; cur <= end - EXT4_FC_TAG_BASE_LEN; cur = cur + EXT4_FC_TAG_BASE_LEN + tl.fc_len) { ext4_fc_get_tl(&tl, cur); val = cur + EXT4_FC_TAG_BASE_LEN;