On Fri, Oct 12, 2012 at 10:46:34AM -0700, Kees Cook wrote:
> On Fri, Oct 12, 2012 at 9:56 AM, Fengguang Wu <fengguang.wu@xxxxxxxxx> wrote:
> > FYI, there are new compile warnings show up in
> >
> > tree: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git akpm
> > head: 04b956faad392f46c9a234962a9990196b8e48fc
> > commit: b8763455880e371a81b07599bc66ae94f96dc6d6 [18/86] kernel/sys.c: fix stack memory content leak via UNAME26
> > config: mn10300-asb2364_defconfig # make ARCH=mn10300 asb2364_defconfig
> >
> > All warnings:
> >
> > kernel/sys.c: In function 'override_release':
> > kernel/sys.c:1287:10: warning: comparison of distinct pointer types lacks a cast [enabled by default]
>
> Hrm, I don't see this on my builds. Is this check specific to mn10300
> in some way?
Maybe it's more than mn10300.
(gdb) whatis sizeof(long)
type = int
And size_t (__kernel_size_t) is defined to "unsigned int".
> > vim +1287 kernel/sys.c
> >
> > be27425d Andi Kleen 2011-08-19 1271
> > be27425d Andi Kleen 2011-08-19 1272 if (current->personality & UNAME26) {
> > b8763455 Kees Cook 2012-10-12 1273 const char *rest = UTS_RELEASE;
> > b8763455 Kees Cook 2012-10-12 1274 char buf[65] = { 0 };
> > be27425d Andi Kleen 2011-08-19 1275 int ndots = 0;
> > be27425d Andi Kleen 2011-08-19 1276 unsigned v;
> > b8763455 Kees Cook 2012-10-12 1277 size_t copy;
> > be27425d Andi Kleen 2011-08-19 1278
> > be27425d Andi Kleen 2011-08-19 1279 while (*rest) {
> > be27425d Andi Kleen 2011-08-19 1280 if (*rest == '.' && ++ndots >= 3)
> > be27425d Andi Kleen 2011-08-19 1281 break;
> > be27425d Andi Kleen 2011-08-19 1282 if (!isdigit(*rest) && *rest != '.')
> > be27425d Andi Kleen 2011-08-19 1283 break;
> > be27425d Andi Kleen 2011-08-19 1284 rest++;
> > be27425d Andi Kleen 2011-08-19 1285 }
> > be27425d Andi Kleen 2011-08-19 1286 v = ((LINUX_VERSION_CODE >> 8) & 0xff) + 40;
> > b8763455 Kees Cook 2012-10-12 @1287 copy = min(sizeof(buf), max_t(size_t, 1, len));
>
> Should I change this to min_t(size_t, sizeof(buf), max_t(size_t, 1, len)) ?
clamp_t() looks easier. :-)
Thanks,
Fengguang
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