change m_adj to reclaim unused mbufs instead of zero'ing m_len

when trim'ing space off the back of a chain; this is indirect
solution to a potential null ptr deref

Noticed by:	Coverity Prevent analysis tool (null ptr deref)
Reviewed by:	dg, rwatson

1 files changed, 4 insertions, 2 deletions

diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
index aece312..4d832a8 100644
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -691,12 +691,14 @@ m_adj(struct mbuf *mp, int req_len)
 		for (; m; m = m->m_next) {
 			if (m->m_len >= count) {
 				m->m_len = count;
+				if (m->m_next != NULL) {
+					m_freem(m->m_next);
+					m->m_next = NULL;
+				}
 				break;
 			}
 			count -= m->m_len;
 		}
-		while (m->m_next)
-			(m = m->m_next) ->m_len = 0;
 	}
 }