1 files changed, 33 insertions, 23 deletions

diff --git a/executor/common_linux.h b/executor/common_linux.h
index c4ebf850f..7014f156d 100644
--- a/executor/common_linux.h
+++ b/executor/common_linux.h
@@ -3429,6 +3429,7 @@ static void mount_cgroups(const char* dir, const char** controllers, int count)
 {
 	if (mkdir(dir, 0777)) {
 		debug("mkdir(%s) failed: %d\n", dir, errno);
+		return;
 	}
 	// First, probe one-by-one to understand what controllers are present.
 	char enabled[128] = {0};
@@ -3461,24 +3462,11 @@ static void mount_cgroups(const char* dir, const char** controllers, int count)
 	}
 }
 
-static void setup_cgroups()
+static void mount_cgroups2(const char** controllers, int count)
 {
-	// We want to cover both cgroup and cgroup2.
-	// Each resource controller can be bound to only one of them,
-	// so to cover both we divide all controllers into 3 arbitrary groups.
-	// One group is then bound to cgroup2/unified, and 2 other groups
-	// are bound to 2 cgroup hierarchies.
-	// Note: we need to enable controllers one-by-one for both cgroup and cgroup2.
-	// If we enable all at the same time and one of them fails (b/c of older kernel
-	// or not enabled configs), then all will fail.
-	const char* unified_controllers[] = {"+cpu", "+memory", "+io", "+pids"};
-	const char* net_controllers[] = {"net", "net_prio", "devices", "blkio", "freezer"};
-	const char* cpu_controllers[] = {"cpuset", "cpuacct", "hugetlb", "rlimit"};
-	if (mkdir("/syzcgroup", 0777)) {
-		debug("mkdir(/syzcgroup) failed: %d\n", errno);
-	}
 	if (mkdir("/syzcgroup/unified", 0777)) {
 		debug("mkdir(/syzcgroup/unified) failed: %d\n", errno);
+		return;
 	}
 	if (mount("none", "/syzcgroup/unified", "cgroup2", 0, NULL)) {
 		debug("mount(cgroup2) failed: %d\n", errno);
@@ -3491,19 +3479,41 @@ static void setup_cgroups()
 		// by a previous run of e.g. syz-execprog.
 		if (rmdir("/syzcgroup/unified") && errno != EBUSY)
 			fail("rmdir(/syzcgroup/unified) failed");
+		return;
 	}
 	if (chmod("/syzcgroup/unified", 0777)) {
 		debug("chmod(/syzcgroup/unified) failed: %d\n", errno);
 	}
-	int unified_control = open("/syzcgroup/unified/cgroup.subtree_control", O_WRONLY);
-	if (unified_control != -1) {
-		unsigned i;
-		for (i = 0; i < sizeof(unified_controllers) / sizeof(unified_controllers[0]); i++)
-			if (write(unified_control, unified_controllers[i], strlen(unified_controllers[i])) < 0) {
-				debug("write(cgroup.subtree_control, %s) failed: %d\n", unified_controllers[i], errno);
-			}
-		close(unified_control);
+	int control = open("/syzcgroup/unified/cgroup.subtree_control", O_WRONLY);
+	if (control == -1)
+		return;
+	int i;
+	for (i = 0; i < count; i++)
+		if (write(control, controllers[i], strlen(controllers[i])) < 0) {
+			debug("write(cgroup.subtree_control, %s) failed: %d\n", controllers[i], errno);
+		}
+	close(control);
+}
+
+static void setup_cgroups()
+{
+	// We want to cover both cgroup and cgroup2.
+	// Each resource controller can be bound to only one of them,
+	// so to cover both we divide all controllers into 3 arbitrary groups.
+	// One group is then bound to cgroup2/unified, and 2 other groups
+	// are bound to 2 cgroup hierarchies.
+	// Note: we need to enable controllers one-by-one for both cgroup and cgroup2.
+	// If we enable all at the same time and one of them fails (b/c of older kernel
+	// or not enabled configs), then all will fail.
+	const char* unified_controllers[] = {"+cpu", "+memory", "+io", "+pids"};
+	const char* net_controllers[] = {"net", "net_prio", "devices", "blkio", "freezer"};
+	const char* cpu_controllers[] = {"cpuset", "cpuacct", "hugetlb", "rlimit"};
+	if (mkdir("/syzcgroup", 0777)) {
+		// Can happen due to e.g. read-only file system (EROFS).
+		debug("mkdir(/syzcgroup) failed: %d\n", errno);
+		return;
 	}
+	mount_cgroups2(unified_controllers, sizeof(unified_controllers) / sizeof(unified_controllers[0]));
 	mount_cgroups("/syzcgroup/net", net_controllers, sizeof(net_controllers) / sizeof(net_controllers[0]));
 	mount_cgroups("/syzcgroup/cpu", cpu_controllers, sizeof(cpu_controllers) / sizeof(cpu_controllers[0]));
 	write_file("/syzcgroup/cpu/cgroup.clone_children", "1");