[PATCH] prevent panic during log recovery due to bogus operation header length

[Lachlan McIlroy <lachlan@xxxxxxx>]

A problem was reported where a system panicked in log recovery due
to a corrupt log record.  The cause of the corruption is not known
but this change will at least prevent a crash for this specific
scenario.  Log recovery definitely needs some more work in this area.

Lachlan
--- fs/xfs/xfs_log_recover.c_1.332      2007-12-12 17:14:57.000000000 +1100
+++ fs/xfs/xfs_log_recover.c    2007-12-12 17:15:42.000000000 +1100
@@ -2912,7 +2912,12 @@ xlog_recover_process_data(
                                xlog_recover_new_tid(&rhash[hash], tid,
                                        be64_to_cpu(rhead->h_lsn));
                } else {
-                       ASSERT(dp + be32_to_cpu(ohead->oh_len) <= lp);
+                       if (dp + be32_to_cpu(ohead->oh_len) > lp) {
+                               xlog_warn(
+                       "XFS: xlog_recover_process_data: bad length");
+                               ASSERT(0);
+                               return (XFS_ERROR(EIO));
+                       }
                        flags = ohead->oh_flags & ~XLOG_END_TRANS;
                        if (flags & XLOG_WAS_CONT_TRANS)
                                flags &= ~XLOG_CONTINUE_TRANS;