ext4: add EA_INODE checking to ext4_iget()

Add a new flag, EXT4_IGET_EA_INODE which indicates whether the inode
is expected to have the EA_INODE flag or not.  If the flag is not
set/clear as expected, then fail the iget() operation and mark the
file system as corrupted.

This commit also makes the ext4_iget() always perform the
is_bad_inode() check even when the inode is already inode cache.  This
allows us to remove the is_bad_inode() check from the callers of
ext4_iget() in the ea_inode code.

Reported-by: syzbot+cbb68193bdb95af4340a@syzkaller.appspotmail.com
Reported-by: syzbot+62120febbd1ee3c3c860@syzkaller.appspotmail.com
Reported-by: syzbot+edce54daffee36421b4c@syzkaller.appspotmail.com
Cc: stable@kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20230524034951.779531-2-tytso@mit.edu
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 7 insertions, 29 deletions

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index dfc2e223bd10..a27208129a80 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -433,7 +433,7 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
 		return -EFSCORRUPTED;
 	}
 
-	inode = ext4_iget(parent->i_sb, ea_ino, EXT4_IGET_NORMAL);
+	inode = ext4_iget(parent->i_sb, ea_ino, EXT4_IGET_EA_INODE);
 	if (IS_ERR(inode)) {
 		err = PTR_ERR(inode);
 		ext4_error(parent->i_sb,
@@ -441,23 +441,6 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
 			   err);
 		return err;
 	}
-
-	if (is_bad_inode(inode)) {
-		ext4_error(parent->i_sb,
-			   "error while reading EA inode %lu is_bad_inode",
-			   ea_ino);
-		err = -EIO;
-		goto error;
-	}
-
-	if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
-		ext4_error(parent->i_sb,
-			   "EA inode %lu does not have EXT4_EA_INODE_FL flag",
-			    ea_ino);
-		err = -EINVAL;
-		goto error;
-	}
-
 	ext4_xattr_inode_set_class(inode);
 
 	/*
@@ -478,9 +461,6 @@ static int ext4_xattr_inode_iget(struct inode *parent, unsigned long ea_ino,
 
 	*ea_inode = inode;
 	return 0;
-error:
-	iput(inode);
-	return err;
 }
 
 /* Remove entry from mbcache when EA inode is getting evicted */
@@ -1556,11 +1536,10 @@ ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
 
 	while (ce) {
 		ea_inode = ext4_iget(inode->i_sb, ce->e_value,
-				     EXT4_IGET_NORMAL);
-		if (!IS_ERR(ea_inode) &&
-		    !is_bad_inode(ea_inode) &&
-		    (EXT4_I(ea_inode)->i_flags & EXT4_EA_INODE_FL) &&
-		    i_size_read(ea_inode) == value_len &&
+				     EXT4_IGET_EA_INODE);
+		if (IS_ERR(ea_inode))
+			goto next_entry;
+		if (i_size_read(ea_inode) == value_len &&
 		    !ext4_xattr_inode_read(ea_inode, ea_data, value_len) &&
 		    !ext4_xattr_inode_verify_hashes(ea_inode, NULL, ea_data,
 						    value_len) &&
@@ -1570,9 +1549,8 @@ ext4_xattr_inode_cache_find(struct inode *inode, const void *value,
 			kvfree(ea_data);
 			return ea_inode;
 		}
-
-		if (!IS_ERR(ea_inode))
-			iput(ea_inode);
+		iput(ea_inode);
+	next_entry:
 		ce = mb_cache_entry_find_next(ea_inode_cache, ce);
 	}
 	kvfree(ea_data);