From b18e90e04ac0c6a06518fc9469dc7d12d83db901 Mon Sep 17 00:00:00 2001
From: Aleksandr Nogikh <nogikh@google.com>
Date: Mon, 6 Dec 2021 11:27:33 +0000
Subject: executor: set fixed fd for the extra coverage kcov instance

Currently it is dup2'd to 0, which is quite likely to be closed by the
fuzzer. Dup2 it to a safer fd instead.
---
 executor/executor.cc | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'executor')

diff --git a/executor/executor.cc b/executor/executor.cc
index b11faa684..e4034310d 100644
--- a/executor/executor.cc
+++ b/executor/executor.cc
@@ -71,6 +71,7 @@ const int kPreMmapCoverThreads = 3; // the number of kcov instances to mmap duri
 const int kInPipeFd = kMaxFd - 1; // remapped from stdin
 const int kOutPipeFd = kMaxFd - 2; // remapped from stdout
 const int kCoverFd = kOutPipeFd - kMaxThreads;
+const int kExtraCoverFd = kCoverFd - 1;
 const int kMaxArgs = 9;
 const int kCoverSize = 256 << 10;
 const int kFailStatus = 67;
@@ -477,6 +478,7 @@ int main(int argc, char** argv)
 				thread_mmap_cover(&threads[i]);
 			}
 		}
+		extra_cov.fd = kExtraCoverFd;
 		cover_open(&extra_cov, true);
 		cover_mmap(&extra_cov);
 		cover_protect(&extra_cov);
-- 
cgit mrf-deployment