public inbox for libc-alpha@sourceware.org
 help / color / mirror / Atom feed
From: DJ Delorie <dj@redhat.com>
To: Siddhesh Poyarekar <siddhesh@sourceware.org>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH 1/6] iconv: Remove alloca use in gconv-modules configuration parsing
Date: Mon, 21 Jun 2021 23:17:44 -0400	[thread overview]
Message-ID: <xnbl7y8u5j.fsf@greed.delorie.com> (raw)
In-Reply-To: <20210610111853.2286873-2-siddhesh@sourceware.org>


Siddhesh Poyarekar <siddhesh@sourceware.org> writes:
> The alloca sizes ought to be constrained to PATH_MAX, but replace them
> with dynamic allocation to be safe.  A static PATH_MAX array would
> have worked too but Hurd does not have PATH_MAX and the code path is
> not hot enough to micro-optimise this allocation.  Revisit if any of
> those realities change.
> ---
>  iconv/gconv_conf.c  | 17 +++++++++--------
>  iconv/iconvconfig.c | 17 +++++++++++------
>  2 files changed, 20 insertions(+), 14 deletions(-)
>
> diff --git a/iconv/gconv_conf.c b/iconv/gconv_conf.c
> index c8ad8099a4..3f2cef255b 100644
> --- a/iconv/gconv_conf.c
> +++ b/iconv/gconv_conf.c
> @@ -559,15 +559,15 @@ __gconv_read_conf (void)
>  
>    for (cnt = 0; __gconv_path_elem[cnt].name != NULL; ++cnt)
>      {
> -#define BUF_LEN elem_len + sizeof (gconv_conf_dirname)
> -
>        const char *elem = __gconv_path_elem[cnt].name;
>        size_t elem_len = __gconv_path_elem[cnt].len;
> -      char *buf;
>  
>        /* No slash needs to be inserted between elem and gconv_conf_filename;
>  	 elem already ends in a slash.  */
> -      buf = alloca (BUF_LEN);
> +      char *buf = malloc (elem_len + sizeof (gconv_conf_dirname));
> +      if (buf == NULL)
> +	continue;
> +
>        char *cp = __mempcpy (__mempcpy (buf, elem, elem_len),
>  			    gconv_conf_filename, sizeof (gconv_conf_filename));
>  

replaces alloca with malloc; sizes are the same.  Ok.

> @@ -596,15 +596,16 @@ __gconv_read_conf (void)
>  	      if (len > strlen (suffix)
>  		  && strcmp (ent->d_name + len - strlen (suffix), suffix) == 0)
>  		{
> -		  /* LEN <= PATH_MAX so this alloca is not unbounded.  */
> -		  char *conf = alloca (BUF_LEN + len + 1);
> -		  cp = stpcpy (conf, buf);
> -		  sprintf (cp, "/%s", ent->d_name);
> +		  char *conf;
> +		  if (__asprintf (&conf, "%s/%s", buf, ent->d_name) < 0)
> +		    continue;
>  		  read_conf_file (conf, elem, elem_len, &modules, &nmodules);
> +		  free (conf);

allocated by asprintf, free'd here.  Ok.

>  		}
>  	    }
>  	  __closedir (confdir);
>  	}
> +      free (buf);

Matched free, OK.

>      }
>  #endif
>  
> diff --git a/iconv/iconvconfig.c b/iconv/iconvconfig.c
> index b2a868919c..c9607fb645 100644
> --- a/iconv/iconvconfig.c
> +++ b/iconv/iconvconfig.c
> @@ -712,7 +712,6 @@ handle_file (const char *dir, const char *infile)
>  static int
>  handle_dir (const char *dir)
>  {
> -#define BUF_LEN prefix_len + dirlen + sizeof "gconv-modules.d"
>    char *cp;
>    size_t dirlen = strlen (dir);
>    bool found = false;
> @@ -726,7 +725,10 @@ handle_dir (const char *dir)
>      }
>  
>    /* First, look for a gconv-modules file.  */
> -  char buf[BUF_LEN];
> +  char *buf = malloc (prefix_len + dirlen + sizeof "gconv-modules.d");
> +  if (buf == NULL)
> +    goto out;
> +

Likewise, ok.

>    cp = buf;
>    if (dir[0] == '/')
>      cp = mempcpy (cp, prefix, prefix_len);
> @@ -756,16 +758,19 @@ handle_dir (const char *dir)
>  	  if (len > strlen (suffix)
>  	      && strcmp (ent->d_name + len - strlen (suffix), suffix) == 0)
>  	    {
> -	      /* LEN <= PATH_MAX so this alloca is not unbounded.  */
> -	      char *conf = alloca (BUF_LEN + len + 1);
> -	      cp = stpcpy (conf, buf);
> -	      sprintf (cp, "/%s", ent->d_name);
> +	      char *conf;
> +	      if (asprintf (&conf, "%s/%s", buf, ent->d_name) < 0)
> +		continue;
>  	      found |= handle_file (dir, conf);
> +	      free (conf);

Likewise, ok.

>  	    }
>  	}
>        closedir (confdir);
>      }
>  
> +  free (buf);
> +
> +out:

Freed, ok.

>    if (!found)
>      {
>        error (0, errno, "failed to open gconv configuration files in `%s'",

LGTM.
Reviewed-by: DJ Delorie <dj@redhat.com>


  reply	other threads:[~2021-06-22  3:17 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-10 11:18 [PATCH 0/6] gconv configuration parsing cleanups Siddhesh Poyarekar
2021-06-10 11:18 ` [PATCH 1/6] iconv: Remove alloca use in gconv-modules configuration parsing Siddhesh Poyarekar
2021-06-22  3:17   ` DJ Delorie [this message]
2021-06-10 11:18 ` [PATCH 2/6] gconv_conf: Remove unused variables Siddhesh Poyarekar
2021-06-16 15:28   ` Andreas Schwab
2021-06-22  3:23   ` DJ Delorie
2021-06-10 11:18 ` [PATCH 3/6] gconv_conf: Split out configuration file processing Siddhesh Poyarekar
2021-06-22  3:48   ` DJ Delorie
2021-06-10 11:18 ` [PATCH 4/6] iconvconfig: Use common gconv module parsing function Siddhesh Poyarekar
2021-06-22  4:01   ` DJ Delorie
2021-07-02  9:11   ` Szabolcs Nagy
2021-07-02  9:27     ` Szabolcs Nagy
2021-06-10 11:18 ` [PATCH 5/6] Handle DT_UNKNOWN in gconv-modules.d Siddhesh Poyarekar
2021-06-22  4:03   ` DJ Delorie
2021-06-10 11:18 ` [PATCH 6/6] Add NEWS item for gconv-modules.d change Siddhesh Poyarekar
2021-06-10 11:37   ` Siddhesh Poyarekar
2021-06-16  4:02 ` [PING][PATCH 0/6] gconv configuration parsing cleanups Siddhesh Poyarekar
2021-06-21  9:14 ` [Ping 2][PATCH " Siddhesh Poyarekar

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=xnbl7y8u5j.fsf@greed.delorie.com \
    --to=dj@redhat.com \
    --cc=libc-alpha@sourceware.org \
    --cc=siddhesh@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).