From patchwork Wed Feb 19 16:50:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Schwab X-Patchwork-Id: 38229 Received: (qmail 96713 invoked by alias); 19 Feb 2020 16:50:38 -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 96699 invoked by uid 89); 19 Feb 2020 16:50:38 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-15.3 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, SPF_PASS autolearn=ham version=3.3.1 spammy= X-HELO: mx2.suse.de From: Andreas Schwab To: libc-alpha@sourceware.org Subject: [PATCH] Fix use-after-free in glob when expanding ~user (bug 25414) X-Yow: I'm sitting on my SPEED QUEEN.. To me, it's ENJOYABLE.. I'm WARM.. I'm VIBRATORY.. Date: Wed, 19 Feb 2020 17:50:34 +0100 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 The value of `end_name' points into the value of `dirname', thus don't deallocate the latter before the last use of the former. --- posix/glob.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) diff --git a/posix/glob.c b/posix/glob.c index cba9cd1819..0708ed5ee4 100644 --- a/posix/glob.c +++ b/posix/glob.c @@ -827,31 +827,32 @@ __glob (const char *pattern, int flags, int (*errfunc) (const char *, int), { size_t home_len = strlen (p->pw_dir); size_t rest_len = end_name == NULL ? 0 : strlen (end_name); - char *d; + char *d, *newp; + int use_alloca = glob_use_alloca (alloca_used, + home_len + rest_len + 1); - if (__glibc_unlikely (malloc_dirname)) - free (dirname); - malloc_dirname = 0; - - if (glob_use_alloca (alloca_used, home_len + rest_len + 1)) - dirname = alloca_account (home_len + rest_len + 1, - alloca_used); + if (use_alloca) + newp = alloca_account (home_len + rest_len + 1, alloca_used); else { - dirname = malloc (home_len + rest_len + 1); - if (dirname == NULL) + newp = malloc (home_len + rest_len + 1); + if (newp == NULL) { scratch_buffer_free (&pwtmpbuf); retval = GLOB_NOSPACE; goto out; } - malloc_dirname = 1; } - d = mempcpy (dirname, p->pw_dir, home_len); + d = mempcpy (newp, p->pw_dir, home_len); if (end_name != NULL) d = mempcpy (d, end_name, rest_len); *d = '\0'; + if (__glibc_unlikely (malloc_dirname)) + free (dirname); + dirname = newp; + malloc_dirname = !use_alloca; + dirlen = home_len + rest_len; dirname_modified = 1; }