[Webkit-unassigned] [Bug 242518] IPC::Connection::sendOutputMessage(IPC::UnixMessage&) Syscall param sendmsg(msg.msg_iov[2]) points to uninitialised byte(s)

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=242518

--- Comment #2 from Darin Adler <darin at apple.com> ---
This explains why running under Address Sanitizer on macOS didn’t find this problem.

Having difficulty understanding what is uninitialized. It says:

    msg.msg_iov[2]

The iov vector itself is initialized with memset. The thing that msg_iov[2] points to is initialized by this code:

    iov[iovLength].iov_base = reinterpret_cast<void*>(outputMessage.body());
    iov[iovLength].iov_len = outputMessage.bodySize();

Maybe there’s a problem where outputMessage.body() does not have a suitable lifetime? Or it has uininitialized data in it? Apparently outputMessage is a UnixMessage. May need to look at the construction that makes a UnixMessage from an encoder.

Not sure why valgrind would call the bytes pointed to by msg.msg_iov[2].iov_base just msg.msg_iov[2] but let's assume that is what it means.

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