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

Greg KH
2009-06-09T10:37:33Z

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

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

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

(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>
---
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;