[PATCH 3.16 49/61] ext4: protect journal inode's blocks using block_validity

From: Ben Hutchings <ben@decadent.org.uk>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: akpm@linux-foundation.org, Denis Kirjanov <kda@linux-powerpc.org>,
	"Theodore Ts'o" <tytso@mit.edu>,
	stable@kernel.org
Subject: [PATCH 3.16 49/61] ext4: protect journal inode's blocks using block_validity
Date: Tue, 09 Jun 2020 19:04:40 +0100	[thread overview]
Message-ID: <lsq.1591725832.613622844@decadent.org.uk> (raw)
In-Reply-To: <lsq.1591725831.850867383@decadent.org.uk>

3.16.85-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@mit.edu>

commit 345c0dbf3a30872d9b204db96b5857cd00808cae upstream.

Add the blocks which belong to the journal inode to block_validity's
system zone so attempts to deallocate or overwrite the journal due a
corrupted file system where the journal blocks are also claimed by
another inode.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202879
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
[bwh: Backported to 3.16:
 - Use EXT4_HAS_COMPAT_FEATURE()
 - Use EIO instead of EFSCORRUPTED]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -137,6 +137,48 @@ static void debug_print_tree(struct ext4
 	printk("\n");
 }
 
+static int ext4_protect_reserved_inode(struct super_block *sb, u32 ino)
+{
+	struct inode *inode;
+	struct ext4_sb_info *sbi = EXT4_SB(sb);
+	struct ext4_map_blocks map;
+	u32 i = 0, err = 0, num, n;
+
+	if ((ino < EXT4_ROOT_INO) ||
+	    (ino > le32_to_cpu(sbi->s_es->s_inodes_count)))
+		return -EINVAL;
+	inode = ext4_iget(sb, ino, EXT4_IGET_SPECIAL);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+	num = (inode->i_size + sb->s_blocksize - 1) >> sb->s_blocksize_bits;
+	while (i < num) {
+		map.m_lblk = i;
+		map.m_len = num - i;
+		n = ext4_map_blocks(NULL, inode, &map, 0);
+		if (n < 0) {
+			err = n;
+			break;
+		}
+		if (n == 0) {
+			i++;
+		} else {
+			if (!ext4_data_block_valid(sbi, map.m_pblk, n)) {
+				ext4_error(sb, "blocks %llu-%llu from inode %u "
+					   "overlap system zone", map.m_pblk,
+					   map.m_pblk + map.m_len - 1, ino);
+				err = -EIO;
+				break;
+			}
+			err = add_system_zone(sbi, map.m_pblk, n);
+			if (err < 0)
+				break;
+			i += n;
+		}
+	}
+	iput(inode);
+	return err;
+}
+
 int ext4_setup_system_zone(struct super_block *sb)
 {
 	ext4_group_t ngroups = ext4_get_groups_count(sb);
@@ -171,6 +213,13 @@ int ext4_setup_system_zone(struct super_
 		if (ret)
 			return ret;
 	}
+	if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_HAS_JOURNAL) &&
+	    sbi->s_es->s_journal_inum) {
+		ret = ext4_protect_reserved_inode(sb,
+				le32_to_cpu(sbi->s_es->s_journal_inum));
+		if (ret)
+			return ret;
+	}
 
 	if (test_opt(sb, DEBUG))
 		debug_print_tree(EXT4_SB(sb));
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -411,6 +411,11 @@ static int __check_block_validity(struct
 				unsigned int line,
 				struct ext4_map_blocks *map)
 {
+	if (EXT4_HAS_COMPAT_FEATURE(inode->i_sb,
+				    EXT4_FEATURE_COMPAT_HAS_JOURNAL) &&
+	    (inode->i_ino ==
+	     le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
+		return 0;
 	if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
 				   map->m_len)) {
 		ext4_error_inode(inode, func, line, map->m_pblk,

