From 1228e6c788a0a6f35b9792aaa1ffe20ac72ce1c6 Mon Sep 17 00:00:00 2001
From: Shambhavi Srivastava <shambhavisr@google.com>
Date: Thu, 19 May 2022 18:23:59 -0700
Subject: [PATCH] Adding tests to handle empty size & uint64 overflow in
 parsing size.

PiperOrigin-RevId: 449876821
---
 pkg/sentry/fsimpl/tmpfs/tmpfs.go      | 11 +++++++++--
 pkg/sentry/fsimpl/tmpfs/tmpfs_test.go |  2 ++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index 9ac6d5518..e9fb3b90f 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -972,7 +972,14 @@ func parseSize(s string) (uint64, error) {
 		count = count << 10
 		s = s[:len(s)-1]
 	}
-	bytes, err := strconv.ParseUint(s, 10, 64)
-	bytes = bytes * uint64(count)
+	byteTmp, err := strconv.ParseUint(s, 10, 64)
+	if err != nil {
+		return 0, linuxerr.EINVAL
+	}
+	// Check for overflow.
+	bytes := byteTmp * uint64(count)
+	if byteTmp != 0 && bytes/byteTmp != uint64(count) {
+		return 0, fmt.Errorf("size overflow")
+	}
 	return bytes, err
 }
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs_test.go b/pkg/sentry/fsimpl/tmpfs/tmpfs_test.go
index 2aa58c8ec..df3ad2286 100644
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs_test.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs_test.go
@@ -171,6 +171,8 @@ func TestParseSize(t *testing.T) {
 		{"5P", (5 * 1024 * 1024 * 1024 * 1024 * 1024), false},
 		{"5e", (5 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024), false},
 		{"5e3", 0, true},
+		{"", 0, true},
+		{"9999999999999999P", 0, true},
 	}
 	for _, tt := range tests {
 		testname := fmt.Sprintf("%s", tt.s)