ptrace() a stopped process?

I tried to ptrace() a stopped process and send it SIGCONT;
but gdb seems
to die a horrible death of failed assertion at this.

Is it fundamentally possible in Linux 2.6.17 to ptrace() a
stopped
process?  This is rather important if, say, the process in
question
SIGSTOP'd itself as a knee-jerk to detected memory
corruption and waited
for a debugger.  SIGSTOP will stop all threads in the thread
group and
can't be blocked, trapped, or ignored, so it's perfect for
this.

Drow pointed out to me that redhat does have a patch for
this that never
went in:

http://www.redhat.com/archives/fedor
a-cvs-commits/2005-October/msg00448.html

I was thinking of using this for spawning a child to spawn
gdb and
pausing the parent process when it catches a stack smash
(__stack_chk_fail()) or a heap corruption (glibc
double-free() and
malloc() checks), but there are apparently other mechanisms.
 Still, gdb
dies a horrible death when you try, and if it can get along
fine it
should.

-- 
John Moser <john.r.mosergmail.com>

On Mon, Jul 17, 2006 at 03:19:58PM -0400, John Moser wrote:
> Drow pointed out to me that redhat does have a patch
for this that never
> went in:
> 
> http://www.redhat.com/archives/fedor
a-cvs-commits/2005-October/msg00448.html

They are invited to submit it   Jeff, are
you out there?

-- 
Daniel Jacobowitz
CodeSourcery