shithub: riscv

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ref: 39bf5b987e8ab53a74adec5a15b30f4eda85b357
parent: a9cdbcd5016319901ea112096f042ac9017cdce4
author: cinap_lenrek <[email protected]>
date: Fri May 19 19:42:54 EDT 2023 

devip: don't leak temporary buffers on error

when reading the status files from a conversation, ipread()
allocates a temporary buffer and calls the protocols
generator to fill the buffer and the calls
readstr() to handle the read request.

if the generator or readstr() erors, we must free the
temporary buffer.

also, allocate a more reasonable size for the "local"
and "remote" strings. allocating and zeroing 32K big
buffers for them is excessive.


--- a/sys/src/9/ip/devip.c
+++ b/sys/src/9/ip/devip.c
@@ -610,7 +610,9 @@
 
 enum
 {
-	Statelen=	32*1024,
+	Maxstring=	128,
+	Maxstate=	32*1024,
+	Maxstats=	32*1024,
 };
 
 static long
@@ -647,42 +649,54 @@
 		return netlogread(f, a, offset, n);
 	case Qctl:
 		buf = smalloc(16);
+		if(waserror()){
+			free(buf);
+			nexterror();
+		}
 		snprint(buf, 16, "%lud", CONV(ch->qid));
+	Readstr:
 		rv = readstr(offset, p, n, buf);
 		free(buf);
+		poperror();
 		return rv;
 	case Qremote:
-		buf = smalloc(Statelen);
+		buf = smalloc(Maxstring);
+		if(waserror()){
+			free(buf);
+			nexterror();
+		}
 		x = f->p[PROTO(ch->qid)];
 		c = x->conv[CONV(ch->qid)];
 		if(x->remote == nil) {
-			snprint(buf, Statelen, "%I!%d\n", c->raddr, c->rport);
+			snprint(buf, Maxstring, "%I!%d\n", c->raddr, c->rport);
 		} else {
-			(*x->remote)(c, buf, Statelen-2);
+			(*x->remote)(c, buf, Maxstring);
 		}
-		rv = readstr(offset, p, n, buf);
-		free(buf);
-		return rv;
+		goto Readstr;
 	case Qlocal:
-		buf = smalloc(Statelen);
+		buf = smalloc(Maxstring);
+		if(waserror()){
+			free(buf);
+			nexterror();
+		}
 		x = f->p[PROTO(ch->qid)];
 		c = x->conv[CONV(ch->qid)];
 		if(x->local == nil) {
-			snprint(buf, Statelen, "%I!%d\n", c->laddr, c->lport);
+			snprint(buf, Maxstring, "%I!%d\n", c->laddr, c->lport);
 		} else {
-			(*x->local)(c, buf, Statelen-2);
+			(*x->local)(c, buf, Maxstring);
 		}
-		rv = readstr(offset, p, n, buf);
-		free(buf);
-		return rv;
+		goto Readstr;
 	case Qstatus:
-		buf = smalloc(Statelen);
+		buf = smalloc(Maxstate);
+		if(waserror()){
+			free(buf);
+			nexterror();
+		}
 		x = f->p[PROTO(ch->qid)];
 		c = x->conv[CONV(ch->qid)];
-		(*x->state)(c, buf, Statelen-2);
-		rv = readstr(offset, p, n, buf);
-		free(buf);
-		return rv;
+		(*x->state)(c, buf, Maxstate);
+		goto Readstr;
 	case Qdata:
 		c = f->p[PROTO(ch->qid)]->conv[CONV(ch->qid)];
 		return qread(c->rq, a, n);
@@ -696,11 +710,13 @@
 		x = f->p[PROTO(ch->qid)];
 		if(x->stats == nil)
 			error("stats not implemented");
-		buf = smalloc(Statelen);
-		(*x->stats)(x, buf, Statelen);
-		rv = readstr(offset, p, n, buf);
-		free(buf);
-		return rv;
+		buf = smalloc(Maxstats);
+		if(waserror()){
+			free(buf);
+			nexterror();
+		}
+		(*x->stats)(x, buf, Maxstats);
+		goto Readstr;
 	}
 }