On Tue, Jun 14, 2016 at 1:19 PM, Andrew Morton <[email protected]> wrote: > On Sat, 11 Jun 2016 03:33:08 +0200 Heinrich Schuchardt <[email protected]> > wrote: > >> An undetected overflow may occur in do_proc_dointvec_minmax_conv_param. >> >> ... >> >> --- a/kernel/sysctl.c >> +++ b/kernel/sysctl.c >> @@ -2313,7 +2313,17 @@ static int do_proc_dointvec_minmax_conv(bool *negp, >> unsigned long *lvalp, >> { >> struct do_proc_dointvec_minmax_conv_param *param = data; >> if (write) { >> - int val = *negp ? -*lvalp : *lvalp; >> + int val; >> + >> + if (*negp) { >> + if (*lvalp > (unsigned long) INT_MAX + 1) >> + return -EINVAL; >> + val = -*lvalp; >> + } else { >> + if (*lvalp > (unsigned long) INT_MAX) >> + return -EINVAL; >> + val = *lvalp; >> + } >> if ((param->min && *param->min > val) || >> (param->max && *param->max < val)) >> return -EINVAL; > > hm. > > What happens if someone does > > echo -1 > /proc/foo > > expecting to get 0xffffffff? That's a reasonable shorthand, and if we > change that to spit out EINVAL then people's stuff may break.
If we expect the interface to allow overflows, we should at least add comments to do_proc_dointvec_minmax_conv_param()... -Kees -- Kees Cook Chrome OS & Brillo Security
