[Backport] CVE-2021-21231: Insufficient data validation in V8

Cherry-pick of patch originally reviewed on
https://chromium-review.googlesource.com/c/v8/v8/+/2833911:
Merged: [turbofan] Harden ArrayPrototypePop and ArrayPrototypeShift

Revision: d4aafa4022b718596b3deadcc3cdcb9209896154

[email protected]
BUG=chromium:1198696
NOTRY=true
NOPRESUBMIT=true
NOTREECHECKS=true

Change-Id: I1840ffabbed3a3caab75b0abea1d37d9ed446d3f
Reviewed-by: Georg Neis <[email protected]>
Commit-Queue: Georg Neis <[email protected]>
Cr-Commit-Position: refs/branch-heads/9.0@{#39}
Cr-Branched-From: bd0108b4c88e0d6f2350cb79b5f363fbd02f3eb7-refs/heads/9.0.257@{#1}
Cr-Branched-From: 349bcc6a075411f1a7ce2d866c3dfeefc2efa39d-refs/heads/master@{#73001}
Reviewed-by: Allan Sandfeld Jensen <[email protected]>

Author: GeorgNeis

chromium/v8/src/compiler/js-call-reducer.cc

@@ -4513,24 +4513,30 @@ Reduction JSCallReducer::ReduceArrayPrototypePop(Node* node) {
     }
 
     // Compute the new {length}.
-    length = graph()->NewNode(simplified()->NumberSubtract(), length,
-                              jsgraph()->OneConstant());
+    Node* new_length = graph()->NewNode(simplified()->NumberSubtract(),
+                                        length, jsgraph()->OneConstant());
+
+    // This extra check exists solely to break an exploitation technique
+    // that abuses typer mismatches.
+    new_length = efalse = graph()->NewNode(
+        simplified()->CheckBounds(p.feedback()),
+        new_length, length, efalse, if_false);
 
     // Store the new {length} to the {receiver}.
     efalse = graph()->NewNode(
         simplified()->StoreField(AccessBuilder::ForJSArrayLength(kind)),
-        receiver, length, efalse, if_false);
+        receiver, new_length, efalse, if_false);
 
     // Load the last entry from the {elements}.
     vfalse = efalse = graph()->NewNode(
         simplified()->LoadElement(AccessBuilder::ForFixedArrayElement(kind)),
-        elements, length, efalse, if_false);
+        elements, new_length, efalse, if_false);
 
     // Store a hole to the element we just removed from the {receiver}.
     efalse = graph()->NewNode(
         simplified()->StoreElement(
             AccessBuilder::ForFixedArrayElement(GetHoleyElementsKind(kind))),
-        elements, length, jsgraph()->TheHoleConstant(), efalse, if_false);
+        elements, new_length, jsgraph()->TheHoleConstant(), efalse, if_false);
   }
 
   control = graph()->NewNode(common()->Merge(2), if_true, if_false);
@@ -4683,19 +4689,25 @@ Reduction JSCallReducer::ReduceArrayPrototypeShift(Node* node) {
       }
 
       // Compute the new {length}.
-      length = graph()->NewNode(simplified()->NumberSubtract(), length,
-                                jsgraph()->OneConstant());
+      Node* new_length = graph()->NewNode(simplified()->NumberSubtract(),
+                                          length, jsgraph()->OneConstant());
+
+      // This extra check exists solely to break an exploitation technique
+      // that abuses typer mismatches.
+      new_length = etrue1 = graph()->NewNode(
+          simplified()->CheckBounds(p.feedback()),
+          new_length, length, etrue1, if_true1);
 
       // Store the new {length} to the {receiver}.
       etrue1 = graph()->NewNode(
           simplified()->StoreField(AccessBuilder::ForJSArrayLength(kind)),
-          receiver, length, etrue1, if_true1);
+          receiver, new_length, etrue1, if_true1);
 
       // Store a hole to the element we just removed from the {receiver}.
       etrue1 = graph()->NewNode(
           simplified()->StoreElement(
               AccessBuilder::ForFixedArrayElement(GetHoleyElementsKind(kind))),
-          elements, length, jsgraph()->TheHoleConstant(), etrue1, if_true1);
+          elements, new_length, jsgraph()->TheHoleConstant(), etrue1, if_true1);
     }
 
     Node* if_false1 = graph()->NewNode(common()->IfFalse(), branch1);