Re: vfork(2) behavior not consistent with fork(2)

From: Florian Weimer
Date: Wed Apr 06 2022 - 16:58:52 EST

* Alejandro Colomar:

>> $ sudo ./vfork_newpid
>> vfork_newpid: PID: 8479
>> vfork_newpid: PID 8479 exiting after execve(2): Success
>> print_pid: PID 1 exiting.
> I definitely think this is a kernel (or glibc) bug.
> execve(2) is supposed to _never_ return 0 (and errno 0).
> I submitted a new bug to discuss it.
> Please see <>

It's not clear if this is valid. The syscall function in glibc does not
protect the on-stack return address against overwriting, so it can't be
used to call SYS_vfork on x86.

Can you reproduce this with a true inline syscall, or the glibc vfork
function (which protects the return address)?