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

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>

1 files changed, 11 insertions, 1 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index c6bd6ced3bb7..cab75bbcd57b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4409,7 +4409,17 @@ struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
                         (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
         }
 
-        if (ei->i_flags & EXT4_EXTENTS_FL) {
+        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;
+        } else if (ei->i_flags & EXT4_EXTENTS_FL) {
                 /* Validate extent which is part of inode */
                 ret = ext4_ext_check_inode(inode);
         } else if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||