syz-fuzzer, executor: Add support for blacklisting data race frames

This adds support to add frames that have already been in data races, to
the KCSAN report blacklist.

2 files changed, 33 insertions, 1 deletions

diff --git a/executor/common_linux.h b/executor/common_linux.h
index 5888b65cf..b56453510 100644
--- a/executor/common_linux.h
+++ b/executor/common_linux.h
@@ -2784,9 +2784,33 @@ static void setup_binfmt_misc()
 #endif
 
 #if SYZ_EXECUTOR || SYZ_ENABLE_KCSAN
+#define KCSAN_DEBUGFS_FILE "/sys/kernel/debug/kcsan"
+
 static void setup_kcsan()
 {
-	if (!write_file("/sys/kernel/debug/kcsan", "on"))
+	if (!write_file(KCSAN_DEBUGFS_FILE, "on"))
 		fail("failed to enable KCSAN");
 }
+
+#if SYZ_EXECUTOR // currently only used by executor
+static void setup_kcsan_filterlist(char** frames, int nframes, bool blacklist)
+{
+	int fd = open(KCSAN_DEBUGFS_FILE, O_WRONLY);
+	if (fd == -1)
+		fail("failed to open(\"%s\")", KCSAN_DEBUGFS_FILE);
+
+	const char* const filtertype = blacklist ? "blacklist" : "whitelist";
+	printf("adding functions to KCSAN %s: ", filtertype);
+	dprintf(fd, "%s\n", filtertype);
+	for (int i = 0; i < nframes; ++i) {
+		printf("'%s' ", frames[i]);
+		dprintf(fd, "!%s\n", frames[i]);
+	}
+	printf("\n");
+
+	close(fd);
+}
+
+#define SYZ_HAVE_KCSAN 1
+#endif
 #endif
diff --git a/executor/executor.cc b/executor/executor.cc
index 1f51ec279..30d497ea9 100644
--- a/executor/executor.cc
+++ b/executor/executor.cc
@@ -347,6 +347,14 @@ int main(int argc, char** argv)
 #endif
 		return 0;
 	}
+	if (argc >= 2 && strcmp(argv[1], "setup_kcsan_blacklist") == 0) {
+#if SYZ_HAVE_KCSAN
+		setup_kcsan_filterlist(argv + 2, argc - 2, /*blacklist=*/true);
+#else
+		fail("KCSAN is not implemented");
+#endif
+		return 0;
+	}
 	if (argc == 2 && strcmp(argv[1], "test") == 0)
 		return run_tests();