GIT: unionfs2-2.6.27.y: ext4: Avoid null pointer dereference when decoding EROFS w/o a journal

[Erez Zadok]

commit a3edfd184017a67b30080c1e0d46b91d7306b3d9
Author: Theodore Ts'o <tytso at mit.edu>
Date:   Mon Jul 27 23:09:47 2009 -0400

    ext4: Avoid null pointer dereference when decoding EROFS w/o a journal
    
    commit 78f1ddbb498283c2445c11b0dfa666424c301803 upstream.
    
    We need to check to make sure a journal is present before checking the
    journal flags in ext4_decode_error().
    
    Signed-off-by: Eric Sesterhenn <eric.sesterhenn at lsexperts.de>
    Signed-off-by: "Theodore Ts'o" <tytso at mit.edu>
    Signed-off-by: Greg Kroah-Hartman <gregkh at suse.de>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index db2642a..baacaf8 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -254,7 +254,8 @@ static const char *ext4_decode_error(struct super_block *sb, int errno,
 		errstr = "Out of memory";
 		break;
 	case -EROFS:
-		if (!sb || EXT4_SB(sb)->s_journal->j_flags & JBD2_ABORT)
+		if (!sb || (EXT4_SB(sb)->s_journal &&
+			    EXT4_SB(sb)->s_journal->j_flags & JBD2_ABORT))
 			errstr = "Journal has aborted";
 		else
 			errstr = "Readonly filesystem";