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From:   Ben Hutchings <ben@decadent.org.uk>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
CC:     akpm@linux-foundation.org, "Andreas Dilger" <adilger@dilger.ca>,
        "Theodore Ts'o" <tytso@mit.edu>
Date:   Sun, 11 Nov 2018 19:49:05 +0000
Message-ID: <lsq.1541965745.264978815@decadent.org.uk>
Subject: [PATCH 3.16 080/366] ext4: bubble errors from ext4_find_inline_data_nolock()
 up to ext4_iget()
In-Reply-To: <lsq.1541965744.387173642@decadent.org.uk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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

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

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

commit eb9b5f01c33adebc31cbc236c02695f605b0e417 upstream.

If ext4_find_inline_data_nolock() returns an error it needs to get
reflected up to ext4_iget().  In order to fix this,
ext4_iget_extra_inode() needs to return an error (and not return
void).

This is related to "ext4: do not allow external inodes for inline
data" (which fixes CVE-2018-11412) in that in the errors=continue
case, it would be useful to for userspace to receive an error
indicating that file system is corrupted.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 fs/ext4/inode.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4159,19 +4159,21 @@ static blkcnt_t ext4_inode_blocks(struct
 	}
 }
 
-static inline void ext4_iget_extra_inode(struct inode *inode,
+static inline int ext4_iget_extra_inode(struct inode *inode,
 					 struct ext4_inode *raw_inode,
 					 struct ext4_inode_info *ei)
 {
 	__le32 *magic = (void *)raw_inode +
 			EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
+
 	if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize + sizeof(__le32) <=
 	    EXT4_INODE_SIZE(inode->i_sb) &&
 	    *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
 		ext4_set_inode_state(inode, EXT4_STATE_XATTR);
-		ext4_find_inline_data_nolock(inode);
+		return ext4_find_inline_data_nolock(inode);
 	} else
 		EXT4_I(inode)->i_inline_off = 0;
+	return 0;
 }
 
 struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
@@ -4331,7 +4333,9 @@ struct inode *ext4_iget(struct super_blo
 			ei->i_extra_isize = sizeof(struct ext4_inode) -
 					    EXT4_GOOD_OLD_INODE_SIZE;
 		} else {
-			ext4_iget_extra_inode(inode, raw_inode, ei);
+			ret = ext4_iget_extra_inode(inode, raw_inode, ei);
+			if (ret)
+				goto bad_inode;
 		}
 	}