From a7cad2b092de8430562886ceaa57c14c6eec7763 Mon Sep 17 00:00:00 2001
From: Shambhavi Srivastava <shambhavisr@google.com>
Date: Wed, 11 May 2022 18:33:34 -0700
Subject: [PATCH] Tmpfs with size option enabled bug fix.

Adding test case to check empty size parsing in Linux.
If a value is not passed with size the mount(2) should return EINVAL.
Handling empty size parsing in gVisor.

PiperOrigin-RevId: 448132149
---
 pkg/sentry/fsimpl/tmpfs/tmpfs.go | 5 ++++-
 test/syscalls/linux/mount.cc     | 8 ++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index 432a03490..fabc46f24 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -204,7 +204,7 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
 		delete(mopts, "size")
 		maxSizeInBytes, err := parseSize(maxSizeStr)
 		if err != nil {
-			ctx.Warningf("tmpfs.FilesystemType.GetFilesystem: invalid size: %q", maxSizeStr)
+			ctx.Debugf("tmpfs.FilesystemType.GetFilesystem: parseSize() failed: %v", err)
 			return nil, nil, linuxerr.EINVAL
 		}
 		// Convert size in bytes to nearest Page Size bytes
@@ -948,6 +948,9 @@ func (*fileDescription) Sync(context.Context) error {
 // parseSize converts size in string to an integer bytes.
 // Supported suffixes in string are:K, M, G, T, P, E.
 func parseSize(s string) (uint64, error) {
+	if len(s) == 0 {
+		return 0, fmt.Errorf("size parameter empty")
+	}
 	suffix := s[len(s)-1]
 	count := 1
 	switch suffix {
diff --git a/test/syscalls/linux/mount.cc b/test/syscalls/linux/mount.cc
index 0b127643f..ebb201eda 100644
--- a/test/syscalls/linux/mount.cc
+++ b/test/syscalls/linux/mount.cc
@@ -614,6 +614,14 @@ TEST(MountTest, TmpfsHardLinkAllocCheck) {
   EXPECT_THAT(unlink(fileOne.c_str()), SyscallSucceeds());
 }
 
+// Tests memory allocation for empty size.
+TEST(MountTest, TmpfsEmptySizeAllocCheck) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_SYS_ADMIN)));
+  auto const dir = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDir());
+  ASSERT_THAT(mount("", dir.path().c_str(), "tmpfs", 0, "size"),
+              SyscallFailsWithErrno(EINVAL));
+}
+
 }  // namespace
 
 }  // namespace testing