Messages in this thread | | | Date | Sat, 6 Feb 2010 13:06:40 +0100 | From | Oleg Nesterov <> | Subject | Re: PATCH? process_32.c:__switch_to() calls __math_state_restore() before updating current_task |
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On 02/05, Oleg Nesterov wrote: > > In short: why restore_i387_xstate() does init_fpu() when !used_math(), > can't (or shouldn't) it merely do set_used_math() ? > > restore_i387_xstate: > > if (!used_math()) { > err = init_fpu(tsk); > if (err) > return err; > } > > note that buf != NULL. This means that used_math() was true when > get_sigframe() was called, otherwise buf == sigcontext->fpstate > would be NULL, right? > > So, the task must have the valid ->thread.xstate,
This is probably correct. But a malicious user can set sc->fpsate and fool the kernel, so we must assume buf != NULL implies the valid ->xstate.
Oleg.
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