D7106: fuzz: restrict dirs fuzzer to only 40k of input

[durin42 (Augie Fackler)]

durin42 created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.

REVISION SUMMARY
  Experimentally one very long path of this size shouldn't blow the RAM
  budget in the fuzzer environment, and it's not really exciting to
  discover that building the dirs dict for one stupidly long path uses a
  ton of RAM.

REPOSITORY
  rHG Mercurial

REVISION DETAIL
  https://phab.mercurial-scm.org/D7106

AFFECTED FILES
  contrib/fuzz/dirs.cc

CHANGE DETAILS

diff --git a/contrib/fuzz/dirs.cc b/contrib/fuzz/dirs.cc
--- a/contrib/fuzz/dirs.cc
+++ b/contrib/fuzz/dirs.cc
@@ -35,9 +35,10 @@
 
 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
 {
-	// Don't allow fuzzer inputs larger than 100k, since we'll just bog
-	// down and not accomplish much.
-	if (Size > 100000) {
+	// Don't allow fuzzer inputs larger than 40k: the fuzzer will
+	// discover that if it passes us one extremely long path we'll
+	// use a ton of RAM, which is a surprise to nobody.
+	if (Size > 40000) {
 		return 0;
 	}
 	PyObject *mtext =



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