Merge pull request #9430 from hercules-ci/remove-vlas

Fix stack overflow in `filter`

(cherry picked from commit cb7f25869daa2491eeac5fee49ad8f31b2218c15)
Change-Id: Ib90f97a9805bbb4d0e2741551d490f054fc0a675

1 files changed, 5 insertions, 4 deletions

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index ac8dbeaf1..b906e7747 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -4,6 +4,7 @@
 #include "eval-inline.hh"
 #include "eval.hh"
 #include "eval-settings.hh"
+#include "gc-small-vector.hh"
 #include "globals.hh"
 #include "json-to-value.hh"
 #include "names.hh"
@@ -2726,7 +2727,7 @@ static void prim_catAttrs(EvalState & state, const PosIdx pos, Value * * args, V
     auto attrName = state.symbols.create(state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.catAttrs"));
     state.forceList(*args[1], pos, "while evaluating the second argument passed to builtins.catAttrs");
 
-    Value * res[args[1]->listSize()];
+    SmallValueVector<nonRecursiveStackReservation> res(args[1]->listSize());
     size_t found = 0;
 
     for (auto v2 : args[1]->listItems()) {
@@ -3061,8 +3062,7 @@ static void prim_filter(EvalState & state, const PosIdx pos, Value * * args, Val
 
     state.forceFunction(*args[0], pos, "while evaluating the first argument passed to builtins.filter");
 
-    // FIXME: putting this on the stack is risky.
-    Value * vs[args[1]->listSize()];
+    SmallValueVector<nonRecursiveStackReservation> vs(args[1]->listSize());
     size_t k = 0;
 
     bool same = true;
@@ -3451,7 +3451,8 @@ static void prim_concatMap(EvalState & state, const PosIdx pos, Value * * args,
     state.forceList(*args[1], pos, "while evaluating the second argument passed to builtins.concatMap");
     auto nrLists = args[1]->listSize();
 
-    Value lists[nrLists];
+    // List of returned lists before concatenation. References to these Values must NOT be persisted.
+    SmallTemporaryValueVector<conservativeStackReservation> lists(nrLists);
     size_t len = 0;
 
     for (unsigned int n = 0; n < nrLists; ++n) {