git: 9front

Download patch

ref: 453ed1d3f32b676caeef9b047eaf696bd7899a28
parent: 1f7c0d20c381bebf89c75efbd58ab6c2ea8bc1e7
author: cinap_lenrek <cinap_lenrek@gmx.de>
date: Sun Jun 16 22:28:10 EDT 2013 

ip/ethermedium: drop short packets instead of producing negative size blocks

on usb ethernet, it can happen that we read truncated packets smaller
than the ethernet header size. this produces a warning in pullupblock()
later like: "pullup negative length packet, called from 0xf0199e46"


--- a/sys/src/9/ip/ethermedium.c
+++ b/sys/src/9/ip/ethermedium.c
@@ -354,11 +354,12 @@
 			nexterror();
 		}
 		ifc->in++;
-		bp->rp += ifc->m->hsize;
-		if(ifc->lifc == nil)
+		if(ifc->lifc == nil || BLEN(bp) <= ifc->m->hsize)
 			freeb(bp);
-		else
+		else {
+			bp->rp += ifc->m->hsize;
 			ipiput4(er->f, ifc, bp);
+		}
 		runlock(ifc);
 		poperror();
 	}
@@ -393,11 +394,12 @@
 			nexterror();
 		}
 		ifc->in++;
-		bp->rp += ifc->m->hsize;
-		if(ifc->lifc == nil)
+		if(ifc->lifc == nil || BLEN(bp) <= ifc->m->hsize)
 			freeb(bp);
-		else
+		else {
+			bp->rp += ifc->m->hsize;
 			ipiput6(er->f, ifc, bp);
+		}
 		runlock(ifc);
 		poperror();
 	}
-- 
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