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Aunc.891 NET.eunice utzoo!duke!unc!whm Thu Jun 11 03:06:25 1981 Fun with VMS From: Bill Mitchell (N.C.State University)

Here is a rather odd Eunice problem.

Our system dates from February 1981, I would be interested in knowing if any other people running Eunice can reproduce the following sequence of events.

1) Create a C program: main() { system("hello"); }

2) Create another C program: main() { puts("Hello there."); } Compile and link both, install the first one in [bin] as MAN.EXE. Install the second one in [bin] as HELLO.EXE.

3) From an account without PHY_IO and LOG_IO type: unix man This should print the message "Hello there." on your terminal.

4) Get all the users off the system and log into an account with LOG_IO privelege. (You might want to use a backup disk if you don't trust the VMS disk rebuilding routines.) Type: unix man On our system (VMS 2.2) this will generate a Page Read Error. The process running will be stopped as if a stop/id was entered. Other users will be able to do some things, but eventually there processes will be stopped in the same manner.

If you try to logon, you will get the Username and Password prompts and then the Welcome to Vax.... message, but then your process will die. Another carriage return gets the Username prompt. The only way to stop the system is to halt the processor.

Note that if the program with the system() call is not called "man", it doesn't blow up. (I should just say that man always blows up, others might work too, but I have not tried all permutations of 9 characters.) If the program is not in [bin] it doesn't blow up. And if you don't have the LOG_IO privelege, it doesn't blow up. (once again I haven't checked each and every privelege, but LOG_IO is enough, and hence PHY_IO also).

Perhaps something is getting written into the paging file, so perhaps we are just lucky that it didn't land in INDEXF.SYS.

I have yet to call Kashtan on this matter, so stay tuned for more developments. Bill duke!unc!whm

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