From fc39329736e31a41a82f2fabe9ceb88de4e3a167 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 24 Mar 1999 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1999-03-24

---
 pc/devata.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pc/devata.c b/pc/devata.c
index bd47cecf0904b6422322bf43f61ad64afc2f88de..21066ca8e75ef4b9e8c3b4443b1429febcec0c02 100644
--- a/pc/devata.c
+++ b/pc/devata.c
@@ -865,6 +865,9 @@ ataread(Chan* c, void* a, long n, vlong off)
 	}
 	pp = &dp->p[PART(c->qid.path)];
 
+	if(off < 0)
+		error(Ebadarg);
+
 	buf = smalloc(Maxxfer);
 	if(waserror()){
 		free(buf);
@@ -935,6 +938,9 @@ atawrite(Chan *c, void *a, long n, vlong off)
 	}
 	pp = &dp->p[PART(c->qid.path)];
 
+	if(off < 0)
+		error(Ebadarg);
+
 	buf = smalloc(Maxxfer);
 	if(waserror()){
 		free(buf);