From patchwork Sun Dec 17 17:21:49 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aurelien Jarno X-Patchwork-Id: 24980 Received: (qmail 99975 invoked by alias); 17 Dec 2017 17:22:06 -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 99965 invoked by uid 89); 17 Dec 2017 17:22:06 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-25.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, KAM_LAZY_DOMAIN_SECURITY, T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 spammy= X-HELO: hall.aurel32.net From: Aurelien Jarno To: libc-alpha@sourceware.org Cc: Aurelien Jarno Subject: [PATCH] elf: Check for empty tokens before dynamic string token expansion [BZ #22625] Date: Sun, 17 Dec 2017 18:21:49 +0100 Message-Id: <20171217172149.1748-1-aurelien@aurel32.net> The fillin_rpath function in elf/dl-load.c loops over each RPATH or RUNPATH tokens and intepret empty tokens as the current directory ("./"). In practice the check for empty token is done *after* the dynamic string token expansion. The expansion process can return an empty string for the $ORIGIN token if __libc_enable_secure is set or if the path of the binary can not be determined (/proc not mounted). Fix that by moving the check for empty tokens before the dynamic string token expansion. In addition, check for NULL pointer or empty strings return by expand_dynamic_string_token. The above changed highlighted a bug in decompose_rpath, an empty array is represented by the first element being NULL at the fillin_rpath path level, but by using a -1 pointer in decompose_rpath and other functions. Changelog: [BZ #22625] * elf/dl-load.c (fillin_rpath): Check for empty tokens before dynamic string token expansion. Check for NULL pointer or empty string possibly returned by expand_dynamic_string_token. (decompose_rpath): Check for empty path after dynamic string token expansion. --- ChangeLog | 9 +++++++++ NEWS | 4 ++++ elf/dl-load.c | 30 ++++++++++++++++++++++++++---- 3 files changed, 39 insertions(+), 4 deletions(-) diff --git a/ChangeLog b/ChangeLog index 815e73571d..4ef438d08c 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,12 @@ +2017-12-17 Aurelien Jarno + + [BZ #22625] + * elf/dl-load.c (fillin_rpath): Check for empty tokens before + dynamic string token expansion. Check for NULL pointer or empty + string possibly returned by expand_dynamic_string_token. + (decompose_rpath): Check for empty path after dynamic string + token expansion. + 2017-12-16 Aurelien Jarno [BZ #22505] diff --git a/NEWS b/NEWS index 0670585b4c..8099ecc8f1 100644 --- a/NEWS +++ b/NEWS @@ -149,6 +149,10 @@ Security related changes: CVE-2017-1000366 has been applied, but it is mentioned here only because of the CVE assignment.) Reported by Qualys. + CVE-2017-16997: Incorrect handling of RPATH or RUNPATH containing $ORIGIN + for AT_SECURE or SUID binaries could be used to load libraries from the + current directory. + The following bugs are resolved with this release: [The release manager will add the list generated by diff --git a/elf/dl-load.c b/elf/dl-load.c index bbd3be9e20..81a1a03a01 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -433,14 +433,11 @@ fillin_rpath (char *rpath, struct r_search_path_elem **result, const char *sep, { char *cp; size_t nelems = 0; - char *to_free; + char *to_free = NULL; while ((cp = __strsep (&rpath, sep)) != NULL) { struct r_search_path_elem *dirp; - - to_free = cp = expand_dynamic_string_token (l, cp, 1); - size_t len = strlen (cp); /* `strsep' can pass an empty string. This has to be @@ -450,6 +447,24 @@ fillin_rpath (char *rpath, struct r_search_path_elem **result, const char *sep, static const char curwd[] = "./"; cp = (char *) curwd; } + else + { + to_free = cp = expand_dynamic_string_token (l, cp, 1); + + /* expand_dynamic_string_token can return NULL in case of memory + allocation failure. */ + if (cp == NULL) + continue; + + /* Recompute the length after dynamic string token expansion + and ignore empty paths. */ + len = strlen (cp); + if (len == 0) + { + free (to_free); + continue; + } + } /* Remove trailing slashes (except for "/"). */ while (len > 1 && cp[len - 1] == '/') @@ -620,6 +635,13 @@ decompose_rpath (struct r_search_path_struct *sps, necessary. */ free (copy); + /* There is no path after expansion. */ + if (result[0] == NULL) { + free (result); + sps->dirs = (struct r_search_path_elem **) -1; + return false; + } + sps->dirs = result; /* The caller will change this value if we haven't used a real malloc. */ sps->malloced = 1;