linux-ext4 - [PATCH 1/3] ext4: do not allow external inodes for inline data

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Message-Id: <20180523153714.28470-1-tytso@mit.edu>
Date:   Wed, 23 May 2018 11:37:12 -0400
From:   Theodore Ts'o <tytso@....edu>
To:     Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:     wen.xu@...ech.edu, jannh@...gle.com, Theodore Ts'o <tytso@....edu>
Subject: [PATCH 1/3] ext4: do not allow external inodes for inline data

The inline data feature was implemented before we added support for
external inodes for xattrs.  It makes no sense to support that
combination, but the problem is that there are a number of extended
attribute checks that are skipped if e_value_inum is non-zero.

Unfortunately, the inline data code is completely e_value_inum
unaware, and attempts to interpret the xattr fields as if it were an
inline xattr --- at which point, Hilarty Ensues.

https://bugzilla.kernel.org/show_bug.cgi?id=199803

Reported-by: Jann Horn <jannh@...gle.com>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Fixes: e50e5129f384 ("ext4: xattr-in-inode support")
Cc: stable@...nel.org
---
 fs/ext4/inline.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 70cf4c7b268a..44b4fcdc3755 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -144,6 +144,12 @@ int ext4_find_inline_data_nolock(struct inode *inode)
 		goto out;
 
 	if (!is.s.not_found) {
+		if (is.s.here->e_value_inum) {
+			EXT4_ERROR_INODE(inode, "inline data xattr refers "
+					 "to an external xattr inode");
+			error = -EFSCORRUPTED;
+			goto out;
+		}
 		EXT4_I(inode)->i_inline_off = (u16)((void *)is.s.here -
 					(void *)ext4_raw_inode(&is.iloc));
 		EXT4_I(inode)->i_inline_size = EXT4_MIN_INLINE_DATA_SIZE +
-- 
2.16.1.72.g5be1f00a9a