unix: sendmmsg and recvmsg have to cap a number of message to UIO_MAXIOV

Reported-by: syzbot+f2489ba0b999a45d1ad1@syzkaller.appspotmail.com
PiperOrigin-RevId: 358866218

2 files changed, 22 insertions, 1 deletions

diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index 31dc2525c..1a492bca3 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -2305,7 +2305,7 @@ cc_library(
     name = "socket_generic_test_cases",
     testonly = 1,
     srcs = [
-        "socket_generic.cc",
+        "socket_generic_test_cases.cc",
     ],
     hdrs = [
         "socket_generic.h",
diff --git a/test/syscalls/linux/socket_generic.cc b/test/syscalls/linux/socket_generic_test_cases.cc
index f70047a09..5c4cb6c35 100644
--- a/test/syscalls/linux/socket_generic.cc
+++ b/test/syscalls/linux/socket_generic_test_cases.cc
@@ -98,6 +98,27 @@ TEST_P(AllSocketPairTest, BasicSendmmsg) {
   EXPECT_EQ(0, memcmp(sent_data, received_data, sizeof(sent_data)));
 }
 
+TEST_P(AllSocketPairTest, SendmmsgIsLimitedByMAXIOV) {
+  std::unique_ptr<SocketPair> sockets =
+      ASSERT_NO_ERRNO_AND_VALUE(NewSocketPair());
+  char c = 0;
+
+  std::vector<struct mmsghdr> msgs(UIO_MAXIOV + 1);
+  std::vector<struct iovec> iovs(msgs.size());
+  for (size_t i = 0; i < msgs.size(); i++) {
+    iovs[i].iov_len = 1;
+    iovs[i].iov_base = &c;
+    msgs[i].msg_hdr.msg_iov = &iovs[i];
+    msgs[i].msg_hdr.msg_iovlen = 1;
+  }
+
+  int n;
+  ASSERT_THAT(n = RetryEINTR(sendmmsg)(sockets->first_fd(), msgs.data(),
+                                       msgs.size(), MSG_DONTWAIT),
+              SyscallSucceeds());
+  EXPECT_LE(n, UIO_MAXIOV);
+}
+
 TEST_P(AllSocketPairTest, BasicRecvmmsg) {
   auto sockets = ASSERT_NO_ERRNO_AND_VALUE(NewSocketPair());
   char sent_data[200];