svn commit: r271647 - head/sys/dev/ixgbe

[Adrian Chadd]

Author: adrian
Date: Mon Sep 15 20:50:26 2014
New Revision: 271647
URL: http://svnweb.freebsd.org/changeset/base/271647

Log:
  Fix a double-free of mbufs in rx_ixgbe_discard().
  
  fmp->buf at the free point is already part of the chain being freed,
  so double-freeing is counter-productive.
  
  Submitted by:	Marc De La Gueronniere <mdelagueronniere at verisign.com>
  MFC after:	1 week
  Sponsored by:	Verisign, Inc.

Modified:
  head/sys/dev/ixgbe/ixgbe.c

Modified: head/sys/dev/ixgbe/ixgbe.c
==============================================================================
--- head/sys/dev/ixgbe/ixgbe.c	Mon Sep 15 20:08:07 2014	(r271646)
+++ head/sys/dev/ixgbe/ixgbe.c	Mon Sep 15 20:50:26 2014	(r271647)
@@ -4523,11 +4523,6 @@ ixgbe_rx_discard(struct rx_ring *rxr, in
 
 	rbuf = &rxr->rx_buffers[i];
 
-        if (rbuf->fmp != NULL) {/* Partial chain ? */
-		rbuf->fmp->m_flags |= M_PKTHDR;
-                m_freem(rbuf->fmp);
-                rbuf->fmp = NULL;
-	}
 
 	/*
 	** With advanced descriptors the writeback
@@ -4536,7 +4531,13 @@ ixgbe_rx_discard(struct rx_ring *rxr, in
 	** the normal refresh path to get new buffers
 	** and mapping.
 	*/
-	if (rbuf->buf) {
+
+	if (rbuf->fmp != NULL) {/* Partial chain ? */
+		rbuf->fmp->m_flags |= M_PKTHDR;
+		m_freem(rbuf->fmp);
+		rbuf->fmp = NULL;
+		rbuf->buf = NULL; /* rbuf->buf is part of fmp's chain */
+	} else if (rbuf->buf) {
 		m_free(rbuf->buf);
 		rbuf->buf = NULL;
 	}