From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
To: Joe Simmons-Talbott <josimmon@redhat.com>, libc-alpha@sourceware.org
Subject: Re: [PATCH] setenv.c: Get rid of alloca.
Date: Thu, 29 Jun 2023 11:39:08 -0300 [thread overview]
Message-ID: <afe9f92d-8fdc-7f61-9ea2-5b5403c573f7@linaro.org> (raw)
In-Reply-To: <20230623152517.3268336-1-josimmon@redhat.com>
On 23/06/23 12:25, Joe Simmons-Talbott via Libc-alpha wrote:
> Use a scratch_buffer rather than alloca to avoid potential stack
> overflow.
> ---
> stdlib/setenv.c | 35 ++++++++++-------------------------
> 1 file changed, 10 insertions(+), 25 deletions(-)
>
> diff --git a/stdlib/setenv.c b/stdlib/setenv.c
> index ba5257d3bf..90bc30b219 100644
> --- a/stdlib/setenv.c
> +++ b/stdlib/setenv.c
> @@ -44,6 +44,8 @@ extern int errno;
> # include <unistd.h>
> #endif
>
> +#include <scratch_buffer.h>
> +
There is no use of scratch_buffer, the rest looks ok.
> #if !_LIBC
> # define __environ environ
> # ifndef HAVE_ENVIRON_DECL
> @@ -182,19 +184,14 @@ __add_to_environ (const char *name, const char *value, const char *combined,
> {
> const size_t varlen = namelen + 1 + vallen;
> #ifdef USE_TSEARCH
> - char *new_value;
> - int use_alloca = __libc_use_alloca (varlen);
> - if (__builtin_expect (use_alloca, 1))
> - new_value = (char *) alloca (varlen);
> - else
> + struct scratch_buffer buf;
> + scratch_buffer_init (&buf);
> + if (!scratch_buffer_set_array_size (&buf, 1, varlen))
> {
> - new_value = malloc (varlen);
> - if (new_value == NULL)
> - {
> - UNLOCK;
> - return -1;
> - }
> + UNLOCK;
> + return -1;
> }
> + char *new_value = buf.data;
> # ifdef _LIBC
> __mempcpy (__mempcpy (__mempcpy (new_value, name, namelen), "=", 1),
> value, vallen);
> @@ -209,18 +206,9 @@ __add_to_environ (const char *name, const char *value, const char *combined,
> #endif
> {
> #ifdef USE_TSEARCH
> - if (__glibc_unlikely (! use_alloca))
> - np = new_value;
> - else
> + np = new_value;
> #endif
> {
> - np = malloc (varlen);
> - if (__glibc_unlikely (np == NULL))
> - {
> - UNLOCK;
> - return -1;
> - }
> -
> #ifdef USE_TSEARCH
> memcpy (np, new_value, varlen);
> #else
> @@ -234,10 +222,7 @@ __add_to_environ (const char *name, const char *value, const char *combined,
> }
> #ifdef USE_TSEARCH
> else
> - {
> - if (__glibc_unlikely (! use_alloca))
> - free (new_value);
> - }
> + scratch_buffer_free (&buf);
> #endif
> }
>
next prev parent reply other threads:[~2023-06-29 14:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-23 15:25 Joe Simmons-Talbott
2023-06-26 13:12 ` Carlos O'Donell
2023-06-29 14:39 ` Adhemerval Zanella Netto [this message]
2023-06-29 15:25 ` Joe Simmons-Talbott
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=afe9f92d-8fdc-7f61-9ea2-5b5403c573f7@linaro.org \
--to=adhemerval.zanella@linaro.org \
--cc=josimmon@redhat.com \
--cc=libc-alpha@sourceware.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).