linux-ext4 - [PATCH 3/4] ext4: disallow ea_inodes with extended attributes

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Message-Id: <20230524034951.779531-4-tytso@mit.edu>
Date:   Tue, 23 May 2023 23:49:50 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:     "Theodore Ts'o" <tytso@....edu>, stable@...nel.org,
        syzbot+e44749b6ba4d0434cd47@...kaller.appspotmail.com
Subject: [PATCH 3/4] ext4: disallow ea_inodes with extended attributes

An ea_inode stores the value of an extended attribute; it can not have
extended attributes itself, or this will cause recursive nightmares.
Add a check in ext4_iget() to make sure this is the case.

Cc: stable@...nel.org
Reported-by: syzbot+e44749b6ba4d0434cd47@...kaller.appspotmail.com
Signed-off-by: Theodore Ts'o <tytso@....edu>
---
 fs/ext4/inode.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 258f3cbed347..02de439bf1f0 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4647,6 +4647,9 @@ static const char *check_igot_inode(struct inode *inode, ext4_iget_flags flags)
 	if (flags & EXT4_IGET_EA_INODE) {
 		if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
 			return "missing EA_INODE flag";
+		if (ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
+		    EXT4_I(inode)->i_file_acl)
+			return "ea_inode with extended attributes";
 	} else {
 		if ((EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
 			return "unexpected EA_INODE flag";
-- 
2.31.0