Xen devel - Jun 2008 - [PATCH]: Fix syscall return code when ptrace or audit is active

Attached is a simple patch to fix the return value from the 64-bit kernel when
you call with a bad system call number with tracing enabled (for either ptrace
or audit).  What should happen is that the user process gets a -ENOSYS return
call from the syscall; what actually happens (only in the 64-bit kernel) is that
you get back the system call number.  The 32-bit kernel does not suffer from
this bug, and the pv-ops implementation in the upstream Linux kernel also does
not have this bug.  The attached patch makes the tracesys path look the same as
it does in upstream Linux, and ensures that we return -ENOSYS on this path.

Signed-off-by: Chris Lalancette <clalance@redhat.com>


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On 30/6/08 15:08, "Chris Lalancette" <clalance@redhat.com>
wrote:
> Attached is a simple patch to fix the return value from the 64-bit kernel
when
> you call with a bad system call number with tracing enabled (for either
ptrace
> or audit).  What should happen is that the user process gets a -ENOSYS
return
> call from the syscall; what actually happens (only in the 64-bit kernel) is
> that
> you get back the system call number.  The 32-bit kernel does not suffer
from
> this bug, and the pv-ops implementation in the upstream Linux kernel also
does
> not have this bug.  The attached patch makes the tracesys path look the
same
> as
> it does in upstream Linux, and ensures that we return -ENOSYS on this path.
Thanks. The removal of ''jmp int_ret_from_sys_call'' is not part
of the
bugfix, and also I think the code is clearer if we keep it. So I''ve
applied
all of this patch except the removal of that jmp.

 -- Keir



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Keir Fraser wrote:
> 
> Thanks. The removal of ''jmp int_ret_from_sys_call'' is not
part of the
> bugfix, and also I think the code is clearer if we keep it. So
I''ve applied
> all of this patch except the removal of that jmp.
Oh yes, of course.  Upstream is just letting it fall through.  That''s
fine.  Thanks!

Chris Lalancette

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