[PATCH] Check the value of doi before referencing it

[Huzaifa Sidhpurwala <huzaifas@redhat.com>]

Value of doi is not checked before referencing it.
Though this does not cause any null pointer dereference since
all the callers of cipso_v4_doi_add check the value of doi
before calling the function, but it would be a good programming
practice to do so anyways :)

Signed-off-by: Huzaifa Sidhpurwala <huzaifas@redhat.com>
---
 net/ipv4/cipso_ipv4.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index a0af7ea..7adc4ea 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -473,10 +473,13 @@ int cipso_v4_doi_add(struct cipso_v4_doi *doi_def,
 	u32 doi_type;
 	struct audit_buffer *audit_buf;
 
-	doi = doi_def->doi;
-	doi_type = doi_def->type;
+	if (doi_def) {
+		doi = doi_def->doi;
+		doi_type = doi_def->type;
+	} else
+	goto doi_add_return;
 
-	if (doi_def == NULL || doi_def->doi == CIPSO_V4_DOI_UNKNOWN)
+	if (doi_def->doi == CIPSO_V4_DOI_UNKNOWN)
 		goto doi_add_return;
 	for (iter = 0; iter < CIPSO_V4_TAG_MAXCNT; iter++) {
 		switch (doi_def->tags[iter]) {
-- 
1.7.1