Changeset 276527 in webkit for trunk/Source/JavaScriptCore/yarr/YarrInterpreter.cpp

Timestamp:

Apr 23, 2021, 4:06:12 PM (4 years ago)

Author:

[email protected]

Message:

[YARR Interpreter] Improper backtrack of parentheses with non-zero based greedy quantifiers
​https://bugs.webkit.org/show_bug.cgi?id=224983

Reviewed by Mark Lam.

When we backtrack a parentheses with a greedy non zero based quantifier,
we don't properly restore for the case where we hadn't reached the minimum count.
We now save the input position on entry and restore it when we backtrack for
this case. We also properly release the allocated ParenthesesDisjunctionContext's.

• yarr/YarrInterpreter.cpp:

(JSC::Yarr::Interpreter::matchParentheses):
(JSC::Yarr::Interpreter::backtrackParentheses):

File:

• trunk/Source/JavaScriptCore/yarr/YarrInterpreter.cpp (modified) (3 diffs)

trunk/Source/JavaScriptCore/yarr/YarrInterpreter.cpp

@@ -46 +46 @@
 
     struct BackTrackInfoParentheses {
+        uintptr_t begin;
         uintptr_t matchAmount;
         ParenthesesDisjunctionContext* lastContext;
@@ -1023 +1024 @@
         ByteDisjunction* disjunctionBody = term.atom.parenthesesDisjunction;
 
+        backTrack->begin = input.getPos();
         backTrack->matchAmount = 0;
         backTrack->lastContext = nullptr;
@@ -1176 +1178 @@
                 freeParenthesesDisjunctionContext(context);
 
-                if (result != JSRegExpNoMatch || backTrack->matchAmount < term.atom.quantityMinCount)
+                if (backTrack->matchAmount < term.atom.quantityMinCount) {
+                    while (backTrack->matchAmount) {
+                        context = backTrack->lastContext;
+                        resetMatches(term, context);
+                        popParenthesesDisjunctionContext(backTrack);
+                        freeParenthesesDisjunctionContext(context);
+                    }
+
+                    input.setPos(backTrack->begin);
+                    return result;
+                }
+
+                if (result != JSRegExpNoMatch)
                     return result;
             }