From: Michael Brown <mcb30@ipxe.org>
Date: Sun, 29 Nov 2020 11:21:20 +0000 (+0000)
Subject: [netdevice] Do not attempt to unmap a null I/O buffer
X-Git-Tag: v1.21.1~32
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9ff61ab28df1a0d20e1819d387094d220c1580ad;p=thirdparty%2Fipxe.git

[netdevice] Do not attempt to unmap a null I/O buffer

netdev_tx_err() may be called with a null I/O buffer (e.g. to record a
transmit error with no associated buffer).  Avoid a potential null
pointer dereference in the DMA unmapping code path.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
---

diff --git a/src/net/netdevice.c b/src/net/netdevice.c
index f3feca26b..754799cd1 100644
--- a/src/net/netdevice.c
+++ b/src/net/netdevice.c
@@ -392,7 +392,7 @@ void netdev_tx_err ( struct net_device *netdev,
 	}
 
 	/* Unmap I/O buffer, if required */
-	if ( dma_mapped ( &iobuf->map ) )
+	if ( iobuf && dma_mapped ( &iobuf->map ) )
 		iob_unmap ( iobuf );
 
 	/* Discard packet */