From ede8dfab3760afc8063c3418f217e52f7ec70d42 Mon Sep 17 00:00:00 2001
From: Michael Pratt <mpratt@google.com>
Date: Thu, 30 Jan 2020 09:13:36 -0800
Subject: Enforce splice offset limits

Splice must not allow negative offsets. Writes also must not allow offset +
size to overflow int64. Reads are similarly broken, but not just in splice
(b/148095030).

Reported-by: syzbot+0e1ff0b95fb2859b4190@syzkaller.appspotmail.com
PiperOrigin-RevId: 292361208
---
 test/syscalls/linux/splice.cc | 56 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

(limited to 'test/syscalls')

diff --git a/test/syscalls/linux/splice.cc b/test/syscalls/linux/splice.cc
index 85232cb1f..faa1247f6 100644
--- a/test/syscalls/linux/splice.cc
+++ b/test/syscalls/linux/splice.cc
@@ -60,6 +60,62 @@ TEST(SpliceTest, TwoRegularFiles) {
               SyscallFailsWithErrno(EINVAL));
 }
 
+int memfd_create(const std::string& name, unsigned int flags) {
+  return syscall(__NR_memfd_create, name.c_str(), flags);
+}
+
+TEST(SpliceTest, NegativeOffset) {
+  // Create a new pipe.
+  int fds[2];
+  ASSERT_THAT(pipe(fds), SyscallSucceeds());
+  const FileDescriptor rfd(fds[0]);
+  const FileDescriptor wfd(fds[1]);
+
+  // Fill the pipe.
+  std::vector<char> buf(kPageSize);
+  RandomizeBuffer(buf.data(), buf.size());
+  ASSERT_THAT(write(wfd.get(), buf.data(), buf.size()),
+              SyscallSucceedsWithValue(kPageSize));
+
+  // Open the output file as write only.
+  int fd;
+  EXPECT_THAT(fd = memfd_create("negative", 0), SyscallSucceeds());
+  const FileDescriptor out_fd(fd);
+
+  loff_t out_offset = 0xffffffffffffffffull;
+  constexpr int kSize = 2;
+  EXPECT_THAT(splice(rfd.get(), nullptr, out_fd.get(), &out_offset, kSize, 0),
+              SyscallFailsWithErrno(EINVAL));
+}
+
+// Write offset + size overflows int64.
+//
+// This is a regression test for b/148041624.
+TEST(SpliceTest, WriteOverflow) {
+  // Create a new pipe.
+  int fds[2];
+  ASSERT_THAT(pipe(fds), SyscallSucceeds());
+  const FileDescriptor rfd(fds[0]);
+  const FileDescriptor wfd(fds[1]);
+
+  // Fill the pipe.
+  std::vector<char> buf(kPageSize);
+  RandomizeBuffer(buf.data(), buf.size());
+  ASSERT_THAT(write(wfd.get(), buf.data(), buf.size()),
+              SyscallSucceedsWithValue(kPageSize));
+
+  // Open the output file.
+  int fd;
+  EXPECT_THAT(fd = memfd_create("overflow", 0), SyscallSucceeds());
+  const FileDescriptor out_fd(fd);
+
+  // out_offset + kSize overflows INT64_MAX.
+  loff_t out_offset = 0x7ffffffffffffffeull;
+  constexpr int kSize = 3;
+  EXPECT_THAT(splice(rfd.get(), nullptr, out_fd.get(), &out_offset, kSize, 0),
+              SyscallFailsWithErrno(EINVAL));
+}
+
 TEST(SpliceTest, SamePipe) {
   // Create a new pipe.
   int fds[2];
-- 
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