From patchwork Wed Dec 20 20:23:59 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aurelien Jarno X-Patchwork-Id: 25056 Received: (qmail 116190 invoked by alias); 20 Dec 2017 20:24:28 -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 115912 invoked by uid 89); 20 Dec 2017 20:24:15 -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=Hx-languages-length:4000 X-HELO: hall.aurel32.net From: Aurelien Jarno To: libc-alpha@sourceware.org Cc: "Dmitry V . Levin" , Aurelien Jarno Subject: [PATCH v3] elf: Check for empty tokens before dynamic string token expansion [BZ #22625] Date: Wed, 20 Dec 2017 21:23:59 +0100 Message-Id: <20171220202359.7765-1-aurelien@aurel32.net> The fillin_rpath function in elf/dl-load.c loops over each RPATH or RUNPATH tokens and interprets 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 changes highlighted a bug in decompose_rpath, an empty array is represented by the first element being NULL at the fillin_rpath 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 | 10 ++++++++++ NEWS | 4 ++++ elf/dl-load.c | 35 ++++++++++++++++++++++++++--------- 3 files changed, 40 insertions(+), 9 deletions(-) diff --git a/ChangeLog b/ChangeLog index 35d1d102f6..0ed4d0ab15 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,13 @@ +2017-12-20 Aurelien Jarno + Dmitry V. Levin + + [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. + 2017-12-20 Adhemerval Zanella * nptl/Makefile (libpthread-routines): Add pthread_join_common. diff --git a/NEWS b/NEWS index a43ff26e83..0d43e93a17 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 2964464158..955eb49ecb 100644 --- a/elf/dl-load.c +++ b/elf/dl-load.c @@ -414,22 +414,31 @@ fillin_rpath (char *rpath, struct r_search_path_elem **result, const char *sep, { char *cp; size_t nelems = 0; - char *to_free; while ((cp = __strsep (&rpath, sep)) != NULL) { struct r_search_path_elem *dirp; + char *to_free = NULL; + size_t len = 0; - to_free = cp = expand_dynamic_string_token (l, cp, 1); + /* `strsep' can pass an empty string. */ + if (*cp != '\0') + { + to_free = cp = expand_dynamic_string_token (l, cp, 1); - size_t len = strlen (cp); + /* expand_dynamic_string_token can return NULL in case of empty + path or memory allocation failure. */ + if (cp == NULL) + continue; - /* `strsep' can pass an empty string. This has to be - interpreted as `use the current directory'. */ - if (len == 0) - { - static const char curwd[] = "./"; - cp = (char *) curwd; + /* Compute 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 "/"). */ @@ -594,6 +603,14 @@ 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;