From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91AA51A76AF; Tue, 30 Jul 2024 17:22:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722360142; cv=none; b=krhAoilD0WwvDDW9qqpHqL4TZWXKyfUseGXVfXj0CTRWp0rzYGJP4izNePf8Kf5CYDnZbb+ToogUhYFyDFjD3/xQybPiUSkg0zP14W9N/toAu9Wtrx7afz2KjPyb2lshOeHtx2ZS+aq+6YnMM3IUT9aF7vzZDDlkkyD7yeN9nIw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722360142; c=relaxed/simple; bh=UidiqPQNK6XmyCRAGoJDwH/O5AUqbwBHbCqbrZ9iU3E=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Zg+cJoF2qF3pRVfUBqi71D+UMNsaFx2rGTrB3W5deY55WK9yXTHmBrJCoG1UIDSAIlmySDOmC0pfopNTRCgaBP/ez7HFD0caBSLPuo7xYaSvf7JI3tvGxFK1MxRE2H/NNPDLGc2LYlghRlJYQREXkit13LV0stpTaCTSjN6z7fs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LwaRpW2G; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="LwaRpW2G" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9D807C32782; Tue, 30 Jul 2024 17:22:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1722360142; bh=UidiqPQNK6XmyCRAGoJDwH/O5AUqbwBHbCqbrZ9iU3E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LwaRpW2GZD8PIRIwMj2qBCOyyIaIOmhVtDiRPNUgRkfSxVYbuczgGPAvciGXeLWh7 LnBUUttlll4Avdiug/JqQQMShe52ZpdRn9nGCCNKfIzLeDxitHzXIVGb84yoMAqMin qdLqJ/xIOgEnj+gx53G9tHe67tYUlojWTawPkk90= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+ae688d469e36fb5138d0@syzkaller.appspotmail.com, stable@kernel.org, Baokun Li , Jan Kara , Theodore Tso Subject: [PATCH 6.10 592/809] ext4: check dot and dotdot of dx_root before making dir indexed Date: Tue, 30 Jul 2024 17:47:48 +0200 Message-ID: <20240730151748.212466614@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240730151724.637682316@linuxfoundation.org> References: <20240730151724.637682316@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Baokun Li commit 50ea741def587a64e08879ce6c6a30131f7111e7 upstream. Syzbot reports a issue as follows: ============================================ BUG: unable to handle page fault for address: ffffed11022e24fe PGD 23ffee067 P4D 23ffee067 PUD 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 PID: 5079 Comm: syz-executor306 Not tainted 6.10.0-rc5-g55027e689933 #0 Call Trace: make_indexed_dir+0xdaf/0x13c0 fs/ext4/namei.c:2341 ext4_add_entry+0x222a/0x25d0 fs/ext4/namei.c:2451 ext4_rename fs/ext4/namei.c:3936 [inline] ext4_rename2+0x26e5/0x4370 fs/ext4/namei.c:4214 [...] ============================================ The immediate cause of this problem is that there is only one valid dentry for the block to be split during do_split, so split==0 results in out of bounds accesses to the map triggering the issue. do_split unsigned split dx_make_map count = 1 split = count/2 = 0; continued = hash2 == map[split - 1].hash; ---> map[4294967295] The maximum length of a filename is 255 and the minimum block size is 1024, so it is always guaranteed that the number of entries is greater than or equal to 2 when do_split() is called. But syzbot's crafted image has no dot and dotdot in dir, and the dentry distribution in dirblock is as follows: bus dentry1 hole dentry2 free |xx--|xx-------------|...............|xx-------------|...............| 0 12 (8+248)=256 268 256 524 (8+256)=264 788 236 1024 So when renaming dentry1 increases its name_len length by 1, neither hole nor free is sufficient to hold the new dentry, and make_indexed_dir() is called. In make_indexed_dir() it is assumed that the first two entries of the dirblock must be dot and dotdot, so bus and dentry1 are left in dx_root because they are treated as dot and dotdot, and only dentry2 is moved to the new leaf block. That's why count is equal to 1. Therefore add the ext4_check_dx_root() helper function to add more sanity checks to dot and dotdot before starting the conversion to avoid the above issue. Reported-by: syzbot+ae688d469e36fb5138d0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=ae688d469e36fb5138d0 Fixes: ac27a0ec112a ("[PATCH] ext4: initial copy of files from ext3") Cc: stable@kernel.org Signed-off-by: Baokun Li Reviewed-by: Jan Kara Link: https://patch.msgid.link/20240702132349.2600605-2-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o Signed-off-by: Greg Kroah-Hartman --- fs/ext4/namei.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 51 insertions(+), 5 deletions(-) --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -2217,6 +2217,52 @@ static int add_dirent_to_buf(handle_t *h return err ? err : err2; } +static bool ext4_check_dx_root(struct inode *dir, struct dx_root *root) +{ + struct fake_dirent *fde; + const char *error_msg; + unsigned int rlen; + unsigned int blocksize = dir->i_sb->s_blocksize; + char *blockend = (char *)root + dir->i_sb->s_blocksize; + + fde = &root->dot; + if (unlikely(fde->name_len != 1)) { + error_msg = "invalid name_len for '.'"; + goto corrupted; + } + if (unlikely(strncmp(root->dot_name, ".", fde->name_len))) { + error_msg = "invalid name for '.'"; + goto corrupted; + } + rlen = ext4_rec_len_from_disk(fde->rec_len, blocksize); + if (unlikely((char *)fde + rlen >= blockend)) { + error_msg = "invalid rec_len for '.'"; + goto corrupted; + } + + fde = &root->dotdot; + if (unlikely(fde->name_len != 2)) { + error_msg = "invalid name_len for '..'"; + goto corrupted; + } + if (unlikely(strncmp(root->dotdot_name, "..", fde->name_len))) { + error_msg = "invalid name for '..'"; + goto corrupted; + } + rlen = ext4_rec_len_from_disk(fde->rec_len, blocksize); + if (unlikely((char *)fde + rlen >= blockend)) { + error_msg = "invalid rec_len for '..'"; + goto corrupted; + } + + return true; + +corrupted: + EXT4_ERROR_INODE(dir, "Corrupt dir, %s, running e2fsck is recommended", + error_msg); + return false; +} + /* * This converts a one block unindexed directory to a 3 block indexed * directory, and adds the dentry to the indexed directory. @@ -2251,17 +2297,17 @@ static int make_indexed_dir(handle_t *ha brelse(bh); return retval; } + root = (struct dx_root *) bh->b_data; + if (!ext4_check_dx_root(dir, root)) { + brelse(bh); + return -EFSCORRUPTED; + } /* The 0th block becomes the root, move the dirents out */ fde = &root->dotdot; de = (struct ext4_dir_entry_2 *)((char *)fde + ext4_rec_len_from_disk(fde->rec_len, blocksize)); - if ((char *) de >= (((char *) root) + blocksize)) { - EXT4_ERROR_INODE(dir, "invalid rec_len for '..'"); - brelse(bh); - return -EFSCORRUPTED; - } len = ((char *) root) + (blocksize - csum_size) - (char *) de; /* Allocate new block for the 0th block's dirents */