[patch 82/87] ext4: Fix softlockup caused by illegal i_file_acl value in on-disk inode

[Greg KH]

2.6.29-stable review patch.  If anyone has any objections, please let us know.

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

From: "Theodore Ts'o" <tytso@xxxxxxx>

(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@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 fs/ext4/inode.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4351,6 +4351,18 @@ struct inode *ext4_iget(struct super_blo
 			(__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;


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