Hi!
> > > recvfrom01: fix test for invalid message flags
> >
> > Agreed. We have seen in past, that this (.flags = ~MSG_CMSG_COMPAT)
> > leads to undefined behavior.
>
> It appears the difference comes from LTP:
>
> https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/utils/msg_common.h
>
> The flags has 0 value when compiled with -m32, so we never make it pass
> this check:
> if (flags & MSG_CMSG_COMPAT)
> return -EINVAL;
>
> but the kernel definition is rather based on config option:
> #if defined(CONFIG_COMPAT)
> #define MSG_CMSG_COMPAT 0x80000000 /* This message needs 32 bit fixups
> */
> #else
> #define MSG_CMSG_COMPAT 0 /* We never have 32 bit fixups */
> #endif
Tricky.
But looking into the unix_dgram_sendmsg() which should be the one that
gets called in the particular case, the code realy just checks for the
MSG_OOB, just like the the recvmsg() case.
......
err = -EOPNOTSUPP;
if (msg->msg_flags&MSG_OOB)
goto out;
......
So I guess that we should be safe with changing the test the same way as we did
with recvmsg().
> sendmsg01 seems to be the only place where this flag is used.
That is because it has been removed from the recvmsg01.c by the fix
mentioned in this thread. However the header in question stayed included
there...
--
Cyril Hrubis
chru...@suse.cz
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