jfs: don't walk off the end of ealist

Add a check before visiting the members of ea to
make sure each ea stays within the ealist.

Signed-off-by: lei lu <[e-mail]>
Signed-off-by: Dave Kleikamp <[e-mail]>

fs/jfs/xattr.c

···
 		       size_t buf_size)
 {
 	struct jfs_ea_list *ealist;
-	struct jfs_ea *ea;
+	struct jfs_ea *ea, *ealist_end;
 	struct ea_buffer ea_buf;
 	int xattr_size;
 	ssize_t size;
···
 		goto not_found;
 
 	ealist = (struct jfs_ea_list *) ea_buf.xattr;
+	ealist_end = END_EALIST(ealist);
 
 	/* Find the named attribute */
-	for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea))
+	for (ea = FIRST_EA(ealist); ea < ealist_end; ea = NEXT_EA(ea)) {
+		if (unlikely(ea + 1 > ealist_end) ||
+		    unlikely(NEXT_EA(ea) > ealist_end)) {
+			size = -EUCLEAN;
+			goto release;
+		}
+
 		if ((namelen == ea->namelen) &&
 		    memcmp(name, ea->name, namelen) == 0) {
 			/* Found it */
···
 			memcpy(data, value, size);
 			goto release;
 		}
+	}
       not_found:
 	size = -ENODATA;
       release:
···
 	ssize_t size = 0;
 	int xattr_size;
 	struct jfs_ea_list *ealist;
-	struct jfs_ea *ea;
+	struct jfs_ea *ea, *ealist_end;
 	struct ea_buffer ea_buf;
 
 	down_read(&JFS_IP(inode)->xattr_sem);
···
 		goto release;
 
 	ealist = (struct jfs_ea_list *) ea_buf.xattr;
+	ealist_end = END_EALIST(ealist);
 
 	/* compute required size of list */
-	for (ea = FIRST_EA(ealist); ea < END_EALIST(ealist); ea = NEXT_EA(ea)) {
+	for (ea = FIRST_EA(ealist); ea < ealist_end; ea = NEXT_EA(ea)) {
+		if (unlikely(ea + 1 > ealist_end) ||
+		    unlikely(NEXT_EA(ea) > ealist_end)) {
+			size = -EUCLEAN;
+			goto release;
+		}
+
 		if (can_list(ea))
 			size += name_size(ea) + 1;
 	}