fs/fuse: check that a task has a specified file descriptor

Reported-by: syzbot+814105309d2ae8651084@syzkaller.appspotmail.com
PiperOrigin-RevId: 350159452

2 files changed, 43 insertions, 0 deletions

diff --git a/test/fuse/linux/BUILD b/test/fuse/linux/BUILD
index d1fb178e8..2f745bd47 100644
--- a/test/fuse/linux/BUILD
+++ b/test/fuse/linux/BUILD
@@ -235,6 +235,7 @@ cc_binary(
     srcs = ["mount_test.cc"],
     deps = [
         gtest,
+        "//test/util:mount_util",
         "//test/util:temp_path",
         "//test/util:test_main",
         "//test/util:test_util",
diff --git a/test/fuse/linux/mount_test.cc b/test/fuse/linux/mount_test.cc
index a5c2fbb01..8a5478116 100644
--- a/test/fuse/linux/mount_test.cc
+++ b/test/fuse/linux/mount_test.cc
@@ -17,6 +17,7 @@
 #include <sys/mount.h>
 
 #include "gtest/gtest.h"
+#include "test/util/mount_util.h"
 #include "test/util/temp_path.h"
 #include "test/util/test_util.h"
 
@@ -25,6 +26,17 @@ namespace testing {
 
 namespace {
 
+TEST(FuseMount, Success) {
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open("/dev/fuse", O_WRONLY));
+  std::string mopts = absl::StrCat("fd=", std::to_string(fd.get()));
+
+  const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+
+  const auto mount =
+      ASSERT_NO_ERRNO_AND_VALUE(Mount("", dir.path(), "fuse", 0, mopts, 0));
+}
+
 TEST(FuseMount, FDNotParsable) {
   int devfd;
   EXPECT_THAT(devfd = open("/dev/fuse", O_RDWR), SyscallSucceeds());
@@ -35,6 +47,36 @@ TEST(FuseMount, FDNotParsable) {
               SyscallFailsWithErrno(EINVAL));
 }
 
+TEST(FuseMount, NoDevice) {
+  const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+
+  EXPECT_THAT(mount("", dir.path().c_str(), "fuse", 0, ""),
+              SyscallFailsWithErrno(EINVAL));
+}
+
+TEST(FuseMount, ClosedFD) {
+  FileDescriptor f = ASSERT_NO_ERRNO_AND_VALUE(Open("/dev/fuse", O_WRONLY));
+  int fd = f.release();
+  close(fd);
+  std::string mopts = absl::StrCat("fd=", std::to_string(fd));
+
+  const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+
+  EXPECT_THAT(mount("", dir.path().c_str(), "fuse", 0, mopts.c_str()),
+              SyscallFailsWithErrno(EINVAL));
+}
+
+TEST(FuseMount, BadFD) {
+  const auto dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+  auto file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
+  const FileDescriptor fd =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(file.path(), O_RDWR));
+  std::string mopts = absl::StrCat("fd=", std::to_string(fd.get()));
+
+  EXPECT_THAT(mount("", dir.path().c_str(), "fuse", 0, mopts.c_str()),
+              SyscallFailsWithErrno(EINVAL));
+}
+
 }  // namespace
 
 }  // namespace testing