jffs2: Fix memory leak in jffs2_scan_eraseblock() error path

In jffs2_scan_eraseblock(), 'sumptr' is allocated through kmalloc() if
'sumlen' is larger than 'buf_size'. However, it is not deallocated in the
following execution if jffs2_fill_scan_buf() fails, leading to a memory
leak bug. To fix this issue, free 'sumptr' before returning the error.
Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: Richard Weinberger <richard@nod.at>

fs/jffs2/scan.c

@@ -527,10 +527,13 @@ static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblo
 					err = jffs2_fill_scan_buf(c, sumptr, 
 								  jeb->offset + c->sector_size - sumlen,
 								  sumlen - buf_len);				
-					if (err)
+					if (err) {
+						if (sumlen > buf_size)
+							kfree(sumptr);
 						return err;
 					}
 				}
+			}
 
 		}