staging: dgap: fix memory leak in dgap_parsefile()

In dgap_parsefile() char pointers are set with kstrdup()
without checking that some string is allocated to that
char pointer before. This patch frees the memory if already allocated
and then set the poniter with kstrdup().
Signed-off-by: Ronit halder <ronit.crj@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dgap/dgap.c

@@ -672,6 +672,7 @@ static int dgap_parsefile(char **in)
 				pr_err("unexpected end of file");
 				return -1;
 			}
+			kfree(p->u.board.portstr);
 			p->u.board.portstr = kstrdup(s, GFP_KERNEL);
 			if (kstrtol(s, 0, &p->u.board.port)) {
 				pr_err("bad number for IO port");
@@ -690,6 +691,7 @@ static int dgap_parsefile(char **in)
 				pr_err("unexpected end of file");
 				return -1;
 			}
+			kfree(p->u.board.addrstr);
 			p->u.board.addrstr = kstrdup(s, GFP_KERNEL);
 			if (kstrtoul(s, 0, &p->u.board.addr)) {
 				pr_err("bad number for memory address");
@@ -708,6 +710,7 @@ static int dgap_parsefile(char **in)
 				pr_err("unexpected end of file");
 				return -1;
 			}
+			kfree(p->u.board.pcibusstr);
 			p->u.board.pcibusstr = kstrdup(s, GFP_KERNEL);
 			if (kstrtoul(s, 0, &p->u.board.pcibus)) {
 				pr_err("bad number for pci bus");
@@ -719,6 +722,7 @@ static int dgap_parsefile(char **in)
 				pr_err("unexpected end of file");
 				return -1;
 			}
+			kfree(p->u.board.pcislotstr);
 			p->u.board.pcislotstr = kstrdup(s, GFP_KERNEL);
 			if (kstrtoul(s, 0, &p->u.board.pcislot)) {
 				pr_err("bad number for pci slot");
@@ -737,6 +741,7 @@ static int dgap_parsefile(char **in)
 				pr_err("unexpected end of file");
 				return -1;
 			}
+			kfree(p->u.board.method);
 			p->u.board.method = kstrdup(s, GFP_KERNEL);
 			p->u.board.v_method = 1;
 			break;
@@ -751,6 +756,7 @@ static int dgap_parsefile(char **in)
 				pr_err("unexpected end of file");
 				return -1;
 			}
+			kfree(p->u.board.status);
 			p->u.board.status = kstrdup(s, GFP_KERNEL);
 			break;
 
@@ -800,13 +806,15 @@ static int dgap_parsefile(char **in)
 				pr_err("unexpected end of file");
 				return -1;
 			}
-
+			kfree(p->u.board.status);
 			p->u.board.status = kstrdup(s, GFP_KERNEL);
 
 			if (p->type == CNODE) {
+				kfree(p->u.conc.id);
 				p->u.conc.id = kstrdup(s, GFP_KERNEL);
 				p->u.conc.v_id = 1;
 			} else if (p->type == MNODE) {
+				kfree(p->u.module.id);
 				p->u.module.id = kstrdup(s, GFP_KERNEL);
 				p->u.module.v_id = 1;
 			} else {
@@ -1003,6 +1011,7 @@ static int dgap_parsefile(char **in)
 					pr_err("unexpected end of file");
 					return -1;
 				}
+				kfree(p->u.line.cable);
 				p->u.line.cable = kstrdup(s, GFP_KERNEL);
 				p->u.line.v_cable = 1;
 			}
@@ -1044,6 +1053,7 @@ static int dgap_parsefile(char **in)
 					pr_err("unexpected end of file");
 					return -1;
 				}
+				kfree(p->u.conc.connect);
 				p->u.conc.connect = kstrdup(s, GFP_KERNEL);
 				p->u.conc.v_connect = 1;
 			}