Re: [PATCH 1/2] powerpc: ptrace CHECK_FULL_REGS

Yup, I think I ditched most of them.. for some reason I decided it
couldn't happen, but maybe I'm wrong ?

Well, it's a BUG_ON.  It's supposed to be for something that "can't happen".
That's why it's a sanity check, not a wild assertion. ;-)

The 2/2 patch is an example of a bug that CHECK_FULL_REGS catches.
In the status quo, using PTRACE_PEEKUSR in a bug case crashes while using
PTRACE_GETREGS in the same place might get bogus data.  (In the actual bug
thus found, the data is not bogus and only the bit that FULL_REGS checks is.)


Thanks,
Roland

On Mon, 2007-09-24 at 17:59 -0700, Roland McGrath wrote:

quoted

Yup, I think I ditched most of them.. for some reason I decided it
couldn't happen, but maybe I'm wrong ?

Well, it's a BUG_ON.  It's supposed to be for something that "can't happen".
That's why it's a sanity check, not a wild assertion. ;-)

The 2/2 patch is an example of a bug that CHECK_FULL_REGS catches.
In the status quo, using PTRACE_PEEKUSR in a bug case crashes while using
PTRACE_GETREGS in the same place might get bogus data.  (In the actual bug
thus found, the data is not bogus and only the bit that FULL_REGS checks is.)

Fair enough.

Ben.