If mbuf is not writable get a writable copy before invoking

m_pullup(9).

Tested by:	Garrett Cooper < yanefbsd <at> gmail dot com >

1 files changed, 10 insertions, 1 deletions

diff --git a/sys/dev/msk/if_msk.c b/sys/dev/msk/if_msk.c
index cd0512e..cccabcf 100644
--- a/sys/dev/msk/if_msk.c
+++ b/sys/dev/msk/if_msk.c
@@ -2559,7 +2559,16 @@ msk_encap(struct msk_if_softc *sc_if, struct mbuf **m_head)
 		struct ip *ip;
 		struct tcphdr *tcp;
 
-		/* TODO check for M_WRITABLE(m) */
+		if (M_WRITABLE(m) == 0) {
+			/* Get a writable copy. */
+			m = m_dup(*m_head, M_DONTWAIT);
+			m_freem(*m_head);
+			if (m == NULL) {
+				*m_head = NULL;
+				return (ENOBUFS);
+			}
+			*m_head = m;
+		}
 
 		offset = sizeof(struct ether_header);
 		m = m_pullup(m, offset);