Messages in this thread | | | Subject | Re: [PATCH] riscv: Return -EFAULT if copy_to_user() failed in signal.c | From | Ben Dooks <> | Date | Tue, 2 Mar 2021 10:01:18 +0000 |
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On 02/03/2021 07:28, Tiezhu Yang wrote: > copy_to_user() returns the amount left to copy, it should return -EFAULT > if copy to user failed.
This looks technically correct, but the caller (only one) will check for non-zero and will covert that to -EFAULT in setup_rt_frame().
I expect if this change is done, it also needs to be done for the callers too and there's a few others than assume !=0 is an error.
I think it would be easier to define save_fp_state() to return non-zero on error and note it does not return an error code. It may be worth exiting the functio nif the first __copy_to_user fails?
Note: setup_rt_frame -> setup_sigcontext -> save_fp_frame
> > Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> > --- > arch/riscv/kernel/signal.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c > index 65942b3..2238fc5 100644 > --- a/arch/riscv/kernel/signal.c > +++ b/arch/riscv/kernel/signal.c > @@ -67,7 +67,7 @@ static long save_fp_state(struct pt_regs *regs, > fstate_save(current, regs); > err = __copy_to_user(state, ¤t->thread.fstate, sizeof(*state)); > if (unlikely(err)) > - return err; > + return -EFAULT; > > /* We support no other extension state at this time. */ > for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) { > @@ -140,8 +140,12 @@ static long setup_sigcontext(struct rt_sigframe __user *frame, > { > struct sigcontext __user *sc = &frame->uc.uc_mcontext; > long err; > + > /* sc_regs is structured the same as the start of pt_regs */ > err = __copy_to_user(&sc->sc_regs, regs, sizeof(sc->sc_regs)); > + if (unlikely(err)) > + return -EFAULT; > + > /* Save the floating-point state. */ > if (has_fpu) > err |= save_fp_state(regs, &sc->sc_fpregs); >
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