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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200428122019.26826-1-ahajkova@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-12.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 Apr 2020 17:44:16 -0000 On 28/04/2020 09:20, Alexandra Hájková via Libc-alpha wrote: > +/* Execute the file FD refers to, overlaying the running program image. > + ARGV and ENVP are passed to the new program, as for `execve'. */ > +int > +execveat (int dirfd, const char *path, char *const argv[], char *const envp[], > + int flags) > +{ > + /* Avoid implicit array coercion in syscall macros. */ > + INLINE_SYSCALL_CALL (execveat, dirfd, path, &argv[0], &envp[0], flags); > +#ifndef __ASSUME_EXECVEAT > + if (errno != ENOSYS) > + return -1; > + > + int fd = openat (dirfd, path, flags | O_CLOEXEC); > + if (fd < 0) > + return -1; > + Is this subject to a TOCTOU where a thread might close the fd by explicitly reading /proc/self/fd/? > + struct fd_to_filename fdfilename; > + const char *gfilename > + = path != NULL ? path : __fd_to_filename (fd, &fdfilename); > +> + /* We do not need the return value. */ > + __ execve (gfilename, argv, envp); > + > + int save = errno; > + > + /* We come here only if the 'execve' call fails. Determine whether > + /proc is mounted. If not we return ENOSYS. */ > + struct stat st; > + if (stat ("/proc/self/fd", &st) != 0 && errno == ENOENT) > + save = ENOSYS; > + > + close (fd); > + __set_errno (save); > +#endif > + > + return -1; > +}