9os

commit 0e01341d11d51601f3d776a78df8ae447e9dec55
parent 176c9f869a217e82c93d26f837ac2810017438e6
Author: Roberto E. Vargas Caballero <roberto.vargas@midokura.com>
Date:   Thu, 17 Nov 2022 06:33:20 +0100

os9: Protect ref increments in clone()

The segments can be NULL and the parent was accessed without
a lock.

Diffstat:
M
src/os9/proc.c
 | 
14
++++++++++----

1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/src/os9/proc.c b/src/os9/proc.c
@@ -318,17 +318,23 @@ clone(Task *parent)
 	if (!initptable(tp) || !newstack(tp))
 		goto err;
 
-	incref(&parent->text->ref);
+	lock(&parent->m);
 	tp->text = parent->text;
+	if (tp->text)
+		incref(&parent->text->ref);
 
-	incref(&parent->data->ref);
 	tp->data = parent->data;
+	if (tp->data)
+		incref(&parent->data->ref);
 
-	incref(&parent->ns->ref);
 	tp->ns = parent->ns;
+	if (tp->ns)
+		incref(&parent->ns->ref);
 
-	incref(&parent->fds->ref);
 	tp->fds = parent->fds;
+	if (tp->fds)
+		incref(&parent->fds->ref);
+	unlock(&parent->m);
 
 	return tp;