[PATCH] D39212: Check special-case-list regex before insertion.

[Mitch Phillips via Phabricator via llvm-commits]

hctim created this revision.

Checks that the supplied regex to SpecialCaseList::Matcher::insert(..) is non-empty.

Reported by OSS-fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=3688

Verified that this fixes the provided assertion failure (built with {asan, fuzzer}):

  mitchp at mitchp2:~/llvm-build/git-fuzz$ ninja llvm-special-case-list-fuzzer[12/12] Linking CXX executable bin/llvm-special-case-list-fuzzer
  mitchp at mitchp2:~/llvm-build/git-fuzz$ bin/llvm-special-case-list-fuzzer ~/Downloads/clusterfuzz-testcase-6748633157337088 
  INFO: Seed: 1697404507
  INFO: Loaded 1 modules   (18581 inline 8-bit counters): 18581 [0x9e9f60, 0x9ee7f5), 
  INFO: Loaded 1 PC tables (18581 PCs): 18581 [0x9ee7f8,0xa37148), 
  bin/llvm-special-case-list-fuzzer: Running 1 inputs 1 time(s) each.
  Running: /usr/local/google/home/mitchp/Downloads/clusterfuzz-testcase-6748633157337088
  Executed /usr/local/google/home/mitchp/Downloads/clusterfuzz-testcase-6748633157337088 in 0 ms
  ***
  *** NOTE: fuzzing was not performed, you have only
  ***       executed the target code on a fixed set of inputs.
  ***
  mitchp at mitchp2:~/llvm-build/git-fuzz$ 


https://reviews.llvm.org/D39212

Files:
  lib/Support/SpecialCaseList.cpp


Index: lib/Support/SpecialCaseList.cpp
===================================================================
--- lib/Support/SpecialCaseList.cpp
+++ lib/Support/SpecialCaseList.cpp
@@ -28,6 +28,11 @@
 
 bool SpecialCaseList::Matcher::insert(std::string Regexp,
                                       std::string &REError) {
+  if (Regexp.empty()) {
+    REError = "Supplied regexp was blank";
+    return false;
+  }
+
   if (Regex::isLiteralERE(Regexp)) {
     Strings.insert(Regexp);
     return true;


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