[master] d6a127b Fix memory leak of vary string on stevedore alloc fail

[Martin Blix Grydeland]

commit d6a127b09ef6a241c20016e567a65a64a8af5ed4
Author: Martin Blix Grydeland <martin at varnish-software.com>
Date:   Wed Mar 14 13:52:36 2018 +0100

    Fix memory leak of vary string on stevedore alloc fail
    
    If the stevedore failed the object creation, we would leak the temporary
    VSB holding the computed vary string. This patch frees it.
    
    Problem exists in 4.1 and later.

diff --git a/bin/varnishd/cache/cache_fetch.c b/bin/varnishd/cache/cache_fetch.c
index f64cfb4..69dcfcc 100644
--- a/bin/varnishd/cache/cache_fetch.c
+++ b/bin/varnishd/cache/cache_fetch.c
@@ -129,8 +129,12 @@ vbf_beresp2obj(struct busyobj *bo)
 	if (bo->uncacheable)
 		bo->fetch_objcore->flags |= OC_F_PASS;
 
-	if (!vbf_allocobj(bo, l))
+	if (!vbf_allocobj(bo, l)) {
+		if (vary != NULL)
+			VSB_destroy(&vary);
+		AZ(vary);
 		return (-1);
+	}
 
 	if (vary != NULL) {
 		AN(ObjSetAttr(bo->wrk, bo->fetch_objcore, OA_VARY, varyl,