Re: [PATCH V6 08/33] csky: Process management and Signal

[Eric W. Biederman]

Guo Ren <ren_guo@xxxxxxxxx> writes:

> --- /dev/null
> +++ b/arch/csky/abiv2/fpu.c
> +void fpu_fpe(struct pt_regs * regs)
> +{
> +	int sig;
> +	unsigned int fesr;
> +	siginfo_t info;
> +
> +	fesr = mfcr("cr<2, 2>");
> +
> +	if(fesr & FPE_ILLE){
> +		info.si_code = ILL_ILLOPC;
> +		sig = SIGILL;
> +	}
> +	else if(fesr & FPE_IDC){
> +		info.si_code = ILL_ILLOPN;
> +		sig = SIGILL;
> +	}
> +	else if(fesr & FPE_FEC){
> +		sig = SIGFPE;
> +		if(fesr & FPE_IOC){
> +			info.si_code = FPE_FLTINV;
> +		}
> +		else if(fesr & FPE_DZC){
> +			info.si_code = FPE_FLTDIV;
> +		}
> +		else if(fesr & FPE_UFC){
> +			info.si_code = FPE_FLTUND;
> +		}
> +		else if(fesr & FPE_OFC){
> +			info.si_code = FPE_FLTOVF;
> +		}
> +		else if(fesr & FPE_IXC){
> +			info.si_code = FPE_FLTRES;
> +		}
> +		else {
> +			info.si_code = NSIGFPE;
> +		}
> +	}
> +	else {
> +		info.si_code = NSIGFPE;
> +		sig = SIGFPE;
> +	}
> +	info.si_signo = SIGFPE;
> +	info.si_errno = 0;
> +	info.si_addr = (void *)regs->pc;
> +	force_sig_info(sig, &info, current);
> +}


This use of sending a signal is buggy.  It results in undefined values
being copied to userspace.

Userspace should never be sent NSIGXXX as a si_code.  You can use
FPE_FLTUNK for this default case.

In new code please use force_sig_fault instead of force_sig_info in new
code.  That saves you the trouble of messing with struct siginfo.

Thank you very much,
Eric Biederman