Hello,
[email protected], le ven. 18 sept. 2026 18:07:30 +0200, a ecrit:
> I tested the attached diff and it seems to work.
>
> Your example now has groups 1,2,3 and also sshd works when nscd is enabled.
Good :)
> I am not sure about the extreme cases of n == 0
n==0 should be fine, we'd just keep the egid alone.
> and if n +1 overflows.
You can return EINVAL in that case.
> Also if n is really big there might be problems with the VLA.
Indeed, but we don't really have to care, just like when being given
invalid pointers.
> Is setgroups the only libc function that has the problem?
Mmmm. On GNU/Hurd only we define the equivalent seteuids for uids, I
would say that we would want to have the same behavior, that will be
less surprising to programmers.
Samuel
> diff --git a/sysdeps/mach/hurd/setgroups.c b/sysdeps/mach/hurd/setgroups.c
> index e5a5d59f9c..bcebe10cf5 100644
> --- a/sysdeps/mach/hurd/setgroups.c
> +++ b/sysdeps/mach/hurd/setgroups.c
> @@ -17,6 +17,7 @@
>
> #include <errno.h>
> #include <sys/types.h>
> +#include <unistd.h>
> #include <grp.h>
> #include <hurd.h>
> #include <hurd/id.h>
> @@ -27,12 +28,20 @@ setgroups (size_t n, const gid_t *groups)
> {
> error_t err;
> auth_t newauth;
> - size_t i;
> - gid_t new[n];
> + size_t i, start;
> + gid_t egid;
> + gid_t new[n + 1];
>
> + start = 0;
> + egid = getegid ();
> + if (egid != (gid_t) -1 && n > 0 && egid != groups[0])
> + {
> + new[0] = egid;
> + start = 1;
> + }
> /* Fault before taking locks. */
> for (i = 0; i < n; ++i)
> - new[i] = groups[i];
> + new[i + start] = groups[i];
>
> retry:
> HURD_CRITICAL_BEGIN;
> @@ -45,7 +54,7 @@ retry:
> __auth_makeauth (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
> _hurd_id.gen.uids, _hurd_id.gen.nuids,
> _hurd_id.aux.uids, _hurd_id.aux.nuids,
> - new, n,
> + new, n + start,
> _hurd_id.aux.gids, _hurd_id.aux.ngids,
> &newauth));
> }
--
Samuel
/* Amuse the user in a SPARC fashion */
if (err) printk(
KERN_CRIT " _______________________________ \n"
KERN_CRIT " < Your System ate a SPARC! Gah! >\n"
KERN_CRIT " ------------------------------- \n"
KERN_CRIT " \\ ^__^\n"
KERN_CRIT " \\ (xx)\\_______\n"
KERN_CRIT " (__)\\ )\\/\\\n"
KERN_CRIT " U ||----w |\n"
KERN_CRIT " || ||\n");
(From linux/arch/parisc/kernel/traps.c:die_if_kernel())
