[libc-commits] [libc] [libc] More unpoison for recvmsg (PR #117347)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: Michael Jones (michaelrj-google)

<details>
<summary>Changes</summary>

The msghdr struct is very nested which makes it a pain to unpoison. I'm
pretty sure I've got all of it now. I also added a test which should
hopefully exercise the iovec part under sanitizers since I suspect
that's what's been causing issues.


---
Full diff: https://github.com/llvm/llvm-project/pull/117347.diff


2 Files Affected:

- (modified) libc/src/sys/socket/linux/recvmsg.cpp (+1) 
- (modified) libc/test/src/sys/socket/linux/sendmsg_recvmsg_test.cpp (+2) 


``````````diff
diff --git a/libc/src/sys/socket/linux/recvmsg.cpp b/libc/src/sys/socket/linux/recvmsg.cpp
index e42b6346f330a0..647beeede07f57 100644
--- a/libc/src/sys/socket/linux/recvmsg.cpp
+++ b/libc/src/sys/socket/linux/recvmsg.cpp
@@ -41,6 +41,7 @@ LLVM_LIBC_FUNCTION(ssize_t, recvmsg, (int sockfd, msghdr *msg, int flags)) {
   // Unpoison the msghdr, as well as all its components.
   MSAN_UNPOISON(msg, sizeof(msghdr));
   MSAN_UNPOISON(msg->msg_name, msg->msg_namelen);
+  MSAN_UNPOISON(msg->msg_iov, msg->msg_iovlen * sizeof(struct iovec));
 
   for (size_t i = 0; i < msg->msg_iovlen; ++i) {
     MSAN_UNPOISON(msg->msg_iov[i].iov_base, msg->msg_iov[i].iov_len);
diff --git a/libc/test/src/sys/socket/linux/sendmsg_recvmsg_test.cpp b/libc/test/src/sys/socket/linux/sendmsg_recvmsg_test.cpp
index abcb0a3e6e5062..4d3bae1bfe142a 100644
--- a/libc/test/src/sys/socket/linux/sendmsg_recvmsg_test.cpp
+++ b/libc/test/src/sys/socket/linux/sendmsg_recvmsg_test.cpp
@@ -64,6 +64,8 @@ TEST(LlvmLibcSendMsgRecvMsgTest, SucceedsWithSocketPair) {
   ASSERT_EQ(recv_result, static_cast<ssize_t>(MESSAGE_LEN));
   ASSERT_ERRNO_SUCCESS();
 
+  ASSERT_EQ(recv_message.msg_iov->iov_base, reinterpret_cast<void *>(buffer));
+
   ASSERT_STREQ(buffer, TEST_MESSAGE);
 
   // close both ends of the socket

``````````

</details>


https://github.com/llvm/llvm-project/pull/117347