Changeset 276527 in webkit

Timestamp:

Apr 23, 2021, 4:06:12 PM (5 years ago)

Author:

msaboff@apple.com

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):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• yarr/YarrInterpreter.cpp (modified) (3 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2021-04-23  Michael Saboff  <msaboff@apple.com>
+
+        [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):
+
 2021-04-23  Mark Lam  <mark.lam@apple.com>
 

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;
             }