From: Joe Simmons-Talbott <josimmon@redhat.com>
To: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>,
Siddhesh Poyarekar <siddhesh@gotplt.org>,
Joe Simmons-Talbott via Libc-alpha <libc-alpha@sourceware.org>,
Samuel Thibault <samuel.thibault@ens-lyon.org>,
Sergey Bugaev <bugaevc@gmail.com>
Subject: Re: [PATCH] grantpt: Get rid of alloca
Date: Mon, 5 Jun 2023 18:02:39 -0400 [thread overview]
Message-ID: <20230605220239.GV176347@oak> (raw)
In-Reply-To: <d9b118b9-4a9b-dfa7-1aa1-e4af884fd015@linaro.org>
On Mon, Jun 05, 2023 at 03:14:06PM -0300, Adhemerval Zanella Netto wrote:
>
>
> On 05/06/23 10:37, Joe Simmons-Talbott via Libc-alpha wrote:
> > On Mon, Jun 05, 2023 at 03:29:45PM +0200, Florian Weimer wrote:
> >> * Joe Simmons-Talbott via Libc-alpha:
> >>
> >>> Replace alloca with a scratch_buffer to avoid potential stack overflows.
> >>> ---
> >>> sysdeps/unix/grantpt.c | 12 +++++++++++-
> >>> 1 file changed, 11 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/sysdeps/unix/grantpt.c b/sysdeps/unix/grantpt.c
> >>> index 38fce52576..e5d2390bf2 100644
> >>> --- a/sysdeps/unix/grantpt.c
> >>> +++ b/sysdeps/unix/grantpt.c
> >>> @@ -20,6 +20,7 @@
> >>> #include <fcntl.h>
> >>> #include <grp.h>
> >>> #include <limits.h>
> >>> +#include <scratch_buffer.h>
> >>> #include <stdlib.h>
> >>> #include <string.h>
> >>> #include <sys/resource.h>
> >>> @@ -147,7 +148,14 @@ grantpt (int fd)
> >>> /* `sysconf' does not support _SC_GETGR_R_SIZE_MAX.
> >>> Try a moderate value. */
> >>> grbuflen = 1024;
> >>> - grtmpbuf = (char *) __alloca (grbuflen);
> >>> + struct scratch_buffer sbuf;
> >>> + scratch_buffer_init (&sbuf);
> >>> + if (!scratch_buffer_set_array_size (&sbuf, 1, grbuflen))
> >>> + {
> >>> + retval -1;
> >>> + goto cleanup;
> >>> + }
> >>> + grtmpbuf = sbuf.data;
> >>> __getgrnam_r (TTY_GROUP, &grbuf, grtmpbuf, grbuflen, &p);
> >>> if (p != NULL)
> >>> tty_gid = p->gr_gid;
> >>> @@ -255,6 +263,8 @@ grantpt (int fd)
> >>> if (buf != _buf)
> >>> free (buf);
> >>>
> >>> + scratch_buffer_free(sbuf);
> >>> +
> >>> return retval;
> >>> }
> >>> libc_hidden_def (grantpt)
> >>
> >> How did you test this? This code is only used on Hurd due to the
> >> override in sysdeps/unix/sysv/linux/grantpt.c.
> >
> > The only testing I did was a 'make && make check' on x86_64 and i686 linux.
>
> You will need to build for i686-gnu (Hurd) to actually enable this code. Which
> leads to another, which Siddheash has brough, which is --enable-pt_chown does
> make sense to be provided as a configure switch.
I tested this patch today with build-many-glibcs.py for i686-gnu and it
passed 'make check'. Does your second sentence mean that I needed to
pass '--enable-pt_chown' to configure for the test build?
Thanks,
Joe
next prev parent reply other threads:[~2023-06-05 22:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-01 19:58 Joe Simmons-Talbott
2023-06-05 13:29 ` Florian Weimer
2023-06-05 13:37 ` Joe Simmons-Talbott
2023-06-05 18:14 ` Adhemerval Zanella Netto
2023-06-05 22:02 ` Joe Simmons-Talbott [this message]
2023-06-06 6:14 ` Siddhesh Poyarekar
2023-06-07 19:05 ` Zack Weinberg
2023-06-07 0:40 ` Samuel Thibault
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230605220239.GV176347@oak \
--to=josimmon@redhat.com \
--cc=adhemerval.zanella@linaro.org \
--cc=bugaevc@gmail.com \
--cc=fweimer@redhat.com \
--cc=libc-alpha@sourceware.org \
--cc=samuel.thibault@ens-lyon.org \
--cc=siddhesh@gotplt.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).