Problem: strace -ff fails on 2.4.21-rc1
Quoted 11 lines · Ingo Oeser
Quoted 6 lines
# strace -q -o minicom.trc -tt -ff minicom upeek: ptrace(PTRACE_PEEKUSER, ... ): Operation not permitted detach: ptrace(PTRACE_CONT, ...): Operation not permitted Device /dev/ttyS1 lock failed: No child processes. # uname -a Linux d2 2.4.21-rc1 #1 SMP Wed May 7 06:05:31 EDT 2003 i686 unknownIs minicom a SUID binary, like on my machine? E.g. does
ls -la $(which minicom)
Quoted 7 lines
show
-rwxr-sr-x 1 root uucp 130664 Feb 21 1998
/usr/bin/minicom?
SUID binaries cannot be ptrace()d under Linux for security reasons.
No, it's not suid. Rather than do that I changed the permissions
on /dev/ttyS1 so my normal userid could open it.
And the strace works -- until minicom forks and then the trace fails
to attach to the child. Both root and a normal userid fail with the above messages; it works on 2.5.68.
(BTW does minicom work for you on 2.5? It fails with the "No child
processes" message on 2.5.6x here but works on 2.4 when it's not being traced. Just the very act of running it under strace on 2.4 makes it fail the same way it does on 2.5 here. And stracing it on 2.5.66 made it start working again! Something very strange is going on...)