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[Bug libc/12197] New: ptrace seems to clobber pid argument
- From: "eteran at alum dot rit.edu" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sources dot redhat dot com
- Date: Sat, 6 Nov 2010 07:34:26 +0000
- Subject: [Bug libc/12197] New: ptrace seems to clobber pid argument
- Auto-submitted: auto-generated
Summary: ptrace seems to clobber pid argument
Created attachment 5113
test case that fails on my machine.
I have encountered some very weird behavior where calling ptrace with
PTRACE_GETEVENTMSG causes the variable passed as the pid to be set to 0 after
Certainly this is not the expected behavior since the documentation seems to
indicate that the only "out" parameter is the data parameter.
I've created a basic test case that triggers this issue on my system (gentoo
linux x86-64, gcc-4.5.1, glibc-2.11.2-r3, gentoo-sources-2.6.34-r6).
I will attach the test case that I've created. It uses a clone event to give
reason to do a PTRACE_GETEVENTMSG ptrace request. Afterwards, the pid variable
is set to 0 for some reason.
PS: As a side note. I think I understand why ptrace is a variadic function as
this enables variables of different types to be passed. But why is the pid
passed as one of the variadic parameter? That parameter should always be of
type pid_t right? I would have guessed that the prototype could just as easily
long ptrace(enum __ptrace_request request, pid_t pid, ...);
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