ext4: Fix softlockup caused by illegal i_file_acl value in on-disk inode

(cherry picked from commit 485c26ec70f823f2a9cf45982b724893e53a859e)

If the block containing external extended attributes (which is stored
in i_file_acl and i_file_acl_high) is larger than the on-disk
filesystem, the process which tried to access the extended attributes
will endlessly issue kernel printks complaining that
"__find_get_block_slow() failed", locking up that CPU until the system
is forcibly rebooted.

So when we read in the inode, make sure the i_file_acl value is legal,
and if not, flag the filesystem as being corrupted.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2bd8005e475879f4cc5cdc80676636677c39d355..e8e5127e04016cfe476a022d9f70159c2a3a9d90 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4115,6 +4115,18 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
                        (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
        }
 
+       if (ei->i_file_acl &&
+           ((ei->i_file_acl <
+             (le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block) +
+              EXT4_SB(sb)->s_gdb_count)) ||
+            (ei->i_file_acl >= ext4_blocks_count(EXT4_SB(sb)->s_es)))) {
+               ext4_error(sb, __func__,
+                          "bad extended attribute block %llu in inode #%lu",
+                          ei->i_file_acl, inode->i_ino);
+               ret = -EIO;
+               goto bad_inode;
+       }
+
        if (S_ISREG(inode->i_mode)) {
                inode->i_op = &ext4_file_inode_operations;
                inode->i_fop = &ext4_file_operations;