Merge tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

Pull ext4 fixes from Ted Ts'o:
 "Fix bugs that could cause kernel deadlocks or file system corruption
  while moving xattrs to expand the extended inode.

  Also add some sanity checks to the block group descriptors to make
  sure we don't end up overwriting the superblock"

* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: avoid deadlock when expanding inode size
  ext4: properly align shifted xattrs when expanding inodes
  ext4: fix xattr shifting when expanding inodes part 2
  ext4: fix xattr shifting when expanding inodes
  ext4: validate that metadata blocks do not overlap superblock
  ext4: reserve xattr index for the Hurd

1 files changed, 31 insertions, 22 deletions

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 39e9cfb1b371..2eb935ca5d9e 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1353,15 +1353,19 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize,
 	size_t min_offs, free;
 	int total_ino;
 	void *base, *start, *end;
-	int extra_isize = 0, error = 0, tried_min_extra_isize = 0;
+	int error = 0, tried_min_extra_isize = 0;
 	int s_min_extra_isize = le16_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_min_extra_isize);
+	int isize_diff;	/* How much do we need to grow i_extra_isize */
 
 	down_write(&EXT4_I(inode)->xattr_sem);
+	/*
+	 * Set EXT4_STATE_NO_EXPAND to avoid recursion when marking inode dirty
+	 */
+	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);
 retry:
-	if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {
-		up_write(&EXT4_I(inode)->xattr_sem);
-		return 0;
-	}
+	isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;
+	if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
+		goto out;
 
 	header = IHDR(inode, raw_inode);
 	entry = IFIRST(header);
@@ -1382,7 +1386,7 @@ retry:
 		goto cleanup;
 
 	free = ext4_xattr_free_space(last, &min_offs, base, &total_ino);
-	if (free >= new_extra_isize) {
+	if (free >= isize_diff) {
 		entry = IFIRST(header);
 		ext4_xattr_shift_entries(entry,	EXT4_I(inode)->i_extra_isize
 				- new_extra_isize, (void *)raw_inode +
@@ -1390,8 +1394,7 @@ retry:
 				(void *)header, total_ino,
 				inode->i_sb->s_blocksize);
 		EXT4_I(inode)->i_extra_isize = new_extra_isize;
-		error = 0;
-		goto cleanup;
+		goto out;
 	}
 
 	/*
@@ -1414,7 +1417,7 @@ retry:
 		end = bh->b_data + bh->b_size;
 		min_offs = end - base;
 		free = ext4_xattr_free_space(first, &min_offs, base, NULL);
-		if (free < new_extra_isize) {
+		if (free < isize_diff) {
 			if (!tried_min_extra_isize && s_min_extra_isize) {
 				tried_min_extra_isize++;
 				new_extra_isize = s_min_extra_isize;
@@ -1428,7 +1431,7 @@ retry:
 		free = inode->i_sb->s_blocksize;
 	}
 
-	while (new_extra_isize > 0) {
+	while (isize_diff > 0) {
 		size_t offs, size, entry_size;
 		struct ext4_xattr_entry *small_entry = NULL;
 		struct ext4_xattr_info i = {
@@ -1459,7 +1462,7 @@ retry:
 			EXT4_XATTR_SIZE(le32_to_cpu(last->e_value_size)) +
 					EXT4_XATTR_LEN(last->e_name_len);
 			if (total_size <= free && total_size < min_total_size) {
-				if (total_size < new_extra_isize) {
+				if (total_size < isize_diff) {
 					small_entry = last;
 				} else {
 					entry = last;
@@ -1514,22 +1517,22 @@ retry:
 		error = ext4_xattr_ibody_set(handle, inode, &i, is);
 		if (error)
 			goto cleanup;
+		total_ino -= entry_size;
 
 		entry = IFIRST(header);
-		if (entry_size + EXT4_XATTR_SIZE(size) >= new_extra_isize)
-			shift_bytes = new_extra_isize;
+		if (entry_size + EXT4_XATTR_SIZE(size) >= isize_diff)
+			shift_bytes = isize_diff;
 		else
-			shift_bytes = entry_size + size;
+			shift_bytes = entry_size + EXT4_XATTR_SIZE(size);
 		/* Adjust the offsets and shift the remaining entries ahead */
-		ext4_xattr_shift_entries(entry, EXT4_I(inode)->i_extra_isize -
-			shift_bytes, (void *)raw_inode +
-			EXT4_GOOD_OLD_INODE_SIZE + extra_isize + shift_bytes,
-			(void *)header, total_ino - entry_size,
-			inode->i_sb->s_blocksize);
+		ext4_xattr_shift_entries(entry, -shift_bytes,
+			(void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE +
+			EXT4_I(inode)->i_extra_isize + shift_bytes,
+			(void *)header, total_ino, inode->i_sb->s_blocksize);
 
-		extra_isize += shift_bytes;
-		new_extra_isize -= shift_bytes;
-		EXT4_I(inode)->i_extra_isize = extra_isize;
+		isize_diff -= shift_bytes;
+		EXT4_I(inode)->i_extra_isize += shift_bytes;
+		header = IHDR(inode, raw_inode);
 
 		i.name = b_entry_name;
 		i.value = buffer;
@@ -1551,6 +1554,8 @@ retry:
 		kfree(bs);
 	}
 	brelse(bh);
+out:
+	ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);
 	up_write(&EXT4_I(inode)->xattr_sem);
 	return 0;
 
@@ -1562,6 +1567,10 @@ cleanup:
 	kfree(is);
 	kfree(bs);
 	brelse(bh);
+	/*
+	 * We deliberately leave EXT4_STATE_NO_EXPAND set here since inode
+	 * size expansion failed.
+	 */
 	up_write(&EXT4_I(inode)->xattr_sem);
 	return error;
 }