On Fri, Jan 22, 2016 at 04:48:05PM +0200, Ville Syrjälä wrote:
> On Fri, Jan 22, 2016 at 12:51:23PM +0000, Damien Lespiau wrote:
> > We are reading at most sizeof(data) bytes, but then data may not contain
> > a terminating '\0', at least in theory, so strstr() may overflow the
> > stack allocated array.
> >
> > Make sure that data always contains at least one '\0'.
> >
> > Signed-off-by: Damien Lespiau <damien.lespiau@xxxxxxxxx>
> > ---
> > xf86drm.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/xf86drm.c b/xf86drm.c
> > index 7e28b4f..5f587d9 100644
> > --- a/xf86drm.c
> > +++ b/xf86drm.c
> > @@ -2863,7 +2863,7 @@ static int drmParsePciBusInfo(int maj, int min, drmPciBusInfoPtr info)
> > {
> > #ifdef __linux__
> > char path[PATH_MAX + 1];
> > - char data[128];
> > + char data[128 + 1];
> > char *str;
> > int domain, bus, dev, func;
> > int fd, ret;
> > @@ -2874,6 +2874,7 @@ static int drmParsePciBusInfo(int maj, int min, drmPciBusInfoPtr info)
> > return -errno;
> >
> > ret = read(fd, data, sizeof(data));
> > + data[128] = '\0';
>
> Slightly more paranoid would be something along the lines of
> if (ret >= 0)
> data[ret] = '\0';
>
> But this should be good enough I think so
> Reviewed-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Thanks for the review, pushed!
> The other thing I spotted while looking at the code is the fact that it
> doesn't check the snprint() return value. But I guess PATH_MAX is big
> enough that even if you somehow make maj and min INT_MIN it'll still
> fit.
Right, doesn't seem we can overflow path[].
--
Damien
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