From patchwork Mon Jan 21 15:30:41 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Schwab X-Patchwork-Id: 31137 Received: (qmail 128889 invoked by alias); 21 Jan 2019 15:30:56 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 128869 invoked by uid 89); 21 Jan 2019 15:30:55 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-24.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, SPF_PASS, UNSUBSCRIBE_BODY autolearn=ham version=3.3.2 spammy=Avoid X-HELO: mx1.suse.de From: Andreas Schwab To: libc-alpha@sourceware.org Subject: [PATCH] Avoid concurrency problem in ldconfig (bug 23973) X-Yow: Yow!! It's LIBERACE and TUESDAY WELD!! High on a HILL... driving a LITTLE CAR... I wanna be in that LITTLE CAR, too!! I wanna drive off with LIBBY and TUESDAY! Date: Mon, 21 Jan 2019 16:30:41 +0100 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1.91 (gnu/linux) MIME-Version: 1.0 Use a unique name for the temporary file when updating the ld.so cache, so that two concurrent runs of ldconfig don't write to the same file. * elf/cache.c (save_cache): Use unique temporary name. (save_aux_cache): Likewise. --- elf/cache.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/elf/cache.c b/elf/cache.c index b8e9e6ccc32e..ec7d94b0bc30 100644 --- a/elf/cache.c +++ b/elf/cache.c @@ -427,12 +427,12 @@ save_cache (const char *cache_name) /* Write out the cache. */ /* Write cache first to a temporary file and rename it later. */ - char *temp_name = xmalloc (strlen (cache_name) + 2); - sprintf (temp_name, "%s~", cache_name); + char *temp_name; + if (asprintf (&temp_name, "%s.XXXXXX", cache_name) < 0) + error (EXIT_FAILURE, errno, _("Can't allocate temporary name for cache file")); /* Create file. */ - int fd = open (temp_name, O_CREAT|O_WRONLY|O_TRUNC|O_NOFOLLOW, - S_IRUSR|S_IWUSR); + int fd = mkostemp (temp_name, O_NOFOLLOW); if (fd < 0) error (EXIT_FAILURE, errno, _("Can't create temporary cache file %s"), temp_name); @@ -481,6 +481,7 @@ save_cache (const char *cache_name) free (file_entries_new); free (file_entries); free (strings); + free (temp_name); while (entries) { @@ -804,8 +805,9 @@ save_aux_cache (const char *aux_cache_name) /* Write out auxiliary cache file. */ /* Write auxiliary cache first to a temporary file and rename it later. */ - char *temp_name = xmalloc (strlen (aux_cache_name) + 2); - sprintf (temp_name, "%s~", aux_cache_name); + char *temp_name; + if (asprintf (&temp_name, "%s.XXXXXX", aux_cache_name) < 0) + goto out_fail2; /* Check that directory exists and create if needed. */ char *dir = strdupa (aux_cache_name); @@ -819,8 +821,7 @@ save_aux_cache (const char *aux_cache_name) } /* Create file. */ - int fd = open (temp_name, O_CREAT|O_WRONLY|O_TRUNC|O_NOFOLLOW, - S_IRUSR|S_IWUSR); + int fd = mkostemp (temp_name, O_NOFOLLOW); if (fd < 0) goto out_fail; @@ -840,5 +841,6 @@ save_aux_cache (const char *aux_cache_name) out_fail: /* Free allocated memory. */ free (temp_name); +out_fail2: free (file_entries); }