From: Joe Simmons-Talbott <josimmon@redhat.com>
To: libc-alpha@sourceware.org
Subject: Re: [PATCH] getpw: Get rid of alloca
Date: Mon, 28 Aug 2023 09:21:22 -0400 [thread overview]
Message-ID: <20230828132122.GV3849957@oak> (raw)
In-Reply-To: <20230810134547.GI3849957@oak>
Ping.
On Thu, Aug 10, 2023 at 09:45:47AM -0400, Joe Simmons-Talbott via Libc-alpha wrote:
> On Fri, Jul 07, 2023 at 04:04:00PM -0400, Joe Simmons-Talbott wrote:
> > Use a scratch_buffer rather than alloca to avoid potential stack
> > overflow.
>
> Ping.
>
> Thanks,
> Joe
> > ---
> > pwd/getpw.c | 34 +++++++++++++++++++++++++++-------
> > 1 file changed, 27 insertions(+), 7 deletions(-)
> >
> > diff --git a/pwd/getpw.c b/pwd/getpw.c
> > index cf747374b8..7a27d79910 100644
> > --- a/pwd/getpw.c
> > +++ b/pwd/getpw.c
> > @@ -15,8 +15,8 @@
> > License along with the GNU C Library; if not, see
> > <https://www.gnu.org/licenses/>. */
> >
> > -#include <alloca.h>
> > #include <errno.h>
> > +#include <scratch_buffer.h>
> > #include <stdio.h>
> > #include <unistd.h>
> > #include <pwd.h>
> > @@ -34,28 +34,48 @@ __getpw (__uid_t uid, char *buf)
> > size_t buflen;
> > char *tmpbuf;
> > struct passwd resbuf, *p;
> > + int retval = 0;
> > + struct scratch_buffer sbuf;
> > + scratch_buffer_init (&sbuf);
> >
> > if (buf == NULL)
> > {
> > __set_errno (EINVAL);
> > - return -1;
> > + retval = -1;
> > + goto error_out;
> > }
> >
> > buflen = __sysconf (_SC_GETPW_R_SIZE_MAX);
> > - tmpbuf = alloca (buflen);
> > + if (!scratch_buffer_set_array_size (&sbuf, 1, buflen))
> > + {
> > + retval = -1;
> > + goto error_out;
> > + }
> > + tmpbuf = sbuf.data;
> >
> > if (__getpwuid_r (uid, &resbuf, tmpbuf, buflen, &p) != 0)
> > - return -1;
> > + {
> > + retval = -1;
> > + goto error_out;
> > + }
> >
> > if (p == NULL)
> > - return -1;
> > + {
> > + retval = -1;
> > + goto error_out;
> > + }
> >
> > if (sprintf (buf, "%s:%s:%lu:%lu:%s:%s:%s", p->pw_name, p->pw_passwd,
> > (unsigned long int) p->pw_uid, (unsigned long int) p->pw_gid,
> > p->pw_gecos, p->pw_dir, p->pw_shell) < 0)
> > - return -1;
> > + {
> > + retval = -1;
> > + goto error_out;
> > + }
> >
> > - return 0;
> > +error_out:
> > + scratch_buffer_free (&sbuf);
> > + return retval;
> > }
> > weak_alias (__getpw, getpw)
> >
> > --
> > 2.39.2
> >
>
next prev parent reply other threads:[~2023-08-28 13:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-07 20:04 Joe Simmons-Talbott
2023-08-10 13:45 ` Joe Simmons-Talbott
2023-08-28 13:21 ` Joe Simmons-Talbott [this message]
2023-08-28 17:01 ` Adhemerval Zanella Netto
2023-08-28 20:37 ` Joe Simmons-Talbott
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