File sudo-1.8.10p3-CVE-2017-1000368.patch of Package sudo.18794

commit c13ebffbce208f02c27d8de90a1af95f0aae7fa9
Author: Todd C. Miller <Todd.Miller@courtesan.com>
Date:   Wed May 31 09:14:31 2017 -0600

    A command name may also contain newline characters so read
    /proc/self/stat until EOF.  It is not legal for /proc/self/stat to
    contain embedded NUL bytes so treat the file as corrupt if we see
    any.  With help from Qualys.
    
    This is not exploitable due to the /dev traversal changes in sudo
    1.8.20p1 (thanks Solar!).

Index: sudo-1.8.10p3/src/ttyname.c
===================================================================
--- sudo-1.8.10p3.orig/src/ttyname.c	2017-06-27 10:51:22.550942625 +0200
+++ sudo-1.8.10p3/src/ttyname.c	2017-06-27 10:57:56.797055167 +0200
@@ -429,24 +429,35 @@ get_process_ttyname(void)
 char *
 get_process_ttyname(void)
 {
-    char path[PATH_MAX], *line = NULL, *tty = NULL;
-    size_t linesize = 0;
-    ssize_t len;
-    FILE *fp;
+    char *tty = NULL;
+    const char path[] = "/proc/self/stat";
+    char *cp, buf[1024];
+    ssize_t nread;
+    int fd;
     debug_decl(get_process_ttyname, SUDO_DEBUG_UTIL)
 
-    /* Try to determine the tty from tty_nr in /proc/pid/stat. */
-    snprintf(path, sizeof(path), "/proc/%u/stat", (unsigned int)getpid());
-    if ((fp = fopen(path, "r")) != NULL) {
-	len = getline(&line, &linesize, fp);
-	fclose(fp);
-	if (len != -1) {
+    /*
+     * Try to determine the tty from tty_nr in /proc/self/stat.
+     * Ignore /proc/self/stat if it contains embedded NUL bytes.
+     */
+    if ((fd = open(path, O_RDONLY | O_NOFOLLOW)) != -1) {
+	cp = buf;
+	while ((nread = read(fd, cp, buf + sizeof(buf) - cp)) != 0) {
+	    if (nread == -1) {
+		if (errno == EAGAIN || errno == EINTR)
+		    continue;
+		break;
+	    }
+	    cp += nread;
+	    if (cp >= buf + sizeof(buf))
+		break;
+	}
+	if (nread == 0 && memchr(buf, '\0', cp - buf) == NULL) {
 	    /*
 	     * Field 7 is the tty dev (0 if no tty).
-	     * Since the process name at field 2 "(comm)" may include spaces,
-	     * start at the last ')' found.
 	     */
-	    char *cp = strrchr(line, ')');
+	    *cp = '\0';
+	    cp = strrchr(buf, ')');
 	    if (cp != NULL) {
 		char *ep = cp;
 		const char *errstr;
@@ -470,7 +481,7 @@ get_process_ttyname(void)
 		}
 	    }
 	}
-	efree(line);
+        close(fd);
     }
 
     debug_return_str(tty);