kernel: dont call pprint() while holding up->debug qlock

pprint() might block or even (maliciously) call into
devproc write which will corrupt the qlock chain on attempt
to qlock up->debug again.

1 files changed, 6 insertions, 14 deletions

diff --git a/sys/src/9/alphapc/trap.c b/sys/src/9/alphapc/trap.c
index 556b0bb13..70317bb0c 100644
--- a/sys/src/9/alphapc/trap.c
+++ b/sys/src/9/alphapc/trap.c
@@ -543,9 +543,9 @@ notify(Ureg *ur)
 	}
 
 	if(n->flag != NUser && (up->notified || up->notify==0)) {
+		qunlock(&up->debug);
 		if(n->flag == NDebug)
 			pprint("suicide: %s\n", n->msg);
-		qunlock(&up->debug);
 		pexit(n->msg, n->flag!=NDebug);
 	}
 
@@ -564,9 +564,8 @@ notify(Ureg *ur)
 
 	if(!okaddr((ulong)up->notify, BY2WD, 0)
 	|| !okaddr(sp-ERRMAX-6*BY2WD, sizeof(Ureg)+ERRMAX-6*BY2WD, 1)) {
-		pprint("suicide: bad address or sp in notify\n");
-print("suicide: bad address or sp in notify\n");
 		qunlock(&up->debug);
+		pprint("suicide: bad address or sp in notify\n");
 		pexit("Suicide", 0);
 	}
 
@@ -618,7 +617,6 @@ noted(Ureg *kur, Ureg **urp, ulong arg0)
 	if(arg0!=NRSTR && !up->notified) {
 		qunlock(&up->debug);
 		pprint("call to noted() when not notified\n");
-print("call to noted() when not notified\n");
 		pexit("Suicide", 0);
 	}
 	up->notified = 0;
@@ -630,16 +628,14 @@ print("call to noted() when not notified\n");
 	oureg = (ulong)nur;
 	if((oureg & (BY2V-1))
 	|| !okaddr((ulong)oureg-BY2WD, BY2WD+sizeof(Ureg), 0)){
-		pprint("bad ureg in noted or call to noted() when not notified\n");
-print("bad ureg in noted or call to noted() when not notified\n");
 		qunlock(&up->debug);
+		pprint("bad ureg in noted or call to noted() when not notified\n");
 		pexit("Suicide", 0);
 	}
 
 	if(!validstatus(kur->status, nur->status)) {
 		qunlock(&up->debug);
 		pprint("bad noted ureg status %lux\n", (ulong)nur->status);
-print("bad noted ureg status %lux\n", (ulong)nur->status);
 		pexit("Suicide", 0);
 	}
 
@@ -648,9 +644,8 @@ print("bad noted ureg status %lux\n", (ulong)nur->status);
 	case NCONT:
 	case NRSTR:
 		if(!okaddr(nur->pc, BY2WD, 0) || !okaddr(nur->usp, BY2WD, 0)){
-			pprint("suicide: trap in noted\n");
-print("suicide: trap in noted\n");
 			qunlock(&up->debug);
+			pprint("suicide: trap in noted\n");
 			pexit("Suicide", 0);
 		}
 		up->ureg = (Ureg*)(*(ulong*)(oureg-BY2WD));
@@ -661,9 +656,8 @@ print("suicide: trap in noted\n");
 
 	case NSAVE:
 		if(!okaddr(nur->pc, BY2WD, 0) || !okaddr(nur->usp, BY2WD, 0)){
-			pprint("suicide: trap in noted\n");
-print("suicide: trap in noted\n");
 			qunlock(&up->debug);
+			pprint("suicide: trap in noted\n");
 			pexit("Suicide", 0);
 		}
 		qunlock(&up->debug);
@@ -677,15 +671,13 @@ print("suicide: trap in noted\n");
 		break;
 
 	default:
-		pprint("unknown noted arg 0x%lux\n", arg0);
-print("unknown noted arg 0x%lux\n", arg0);
 		up->lastnote.flag = NDebug;
 		/* fall through */
 		
 	case NDFLT:
+		qunlock(&up->debug);
 		if(up->lastnote.flag == NDebug)
 			pprint("suicide: %s\n", up->lastnote.msg);
-		qunlock(&up->debug);
 		pexit(up->lastnote.msg, up->lastnote.flag!=NDebug);
 	}
 }