From d00c36410b7432fe74485589a750f99fcf05a23f Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Tue, 7 Sep 2021 14:51:14 +0100
Subject: [PATCH] daemon/luks.c: Ignore bogus GCC -fanalyzer double-free
 warning

As far as I can tell the analysis is completely bogus.  We don't
double-free the tempfile string in do_luks_add_key.  Therefore add a
GCC suppression around the remove_temp function.

luks.c: In function 'do_luks_add_key':
luks.c:84:3: error: double-'free' of 'tempfile_14' [CWE-415] [-Werror=analyzer-double-free]
   84 |   free (tempfile);
      |   ^~~~~~~~~~~~~~~
  'do_luks_add_key': events 1-2
    |
    |  143 | do_luks_add_key (const char *device, const char *key, const char *newkey,
    |      | ^~~~~~~~~~~~~~~
    |      | |
    |      | (1) entry to 'do_luks_add_key'
    |......
    |  146 |   char *keyfile = write_key_to_temp (key);
    |      |                   ~~~~~~~~~~~~~~~~~~~~~~~
    |      |                   |
    |      |                   (2) calling 'write_key_to_temp' from 'do_luks_add_key'
    |
    +--> 'write_key_to_temp': events 3-12
           |
           |   41 | write_key_to_temp (const char *key)
           |      | ^~~~~~~~~~~~~~~~~
           |      | |
           |      | (3) entry to 'write_key_to_temp'
           |......
           |   47 |   tempfile = strdup ("/tmp/luksXXXXXX");
           |      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~
           |      |              |
           |      |              (4) allocated here
           |   48 |   if (!tempfile) {
           |      |      ~
           |      |      |
           |      |      (5) assuming 'tempfile_14' is non-NULL
           |      |      (6) following 'false' branch (when 'tempfile_14' is non-NULL)...
           |......
           |   53 |   fd = mkstemp (tempfile);
           |      |   ~~
           |      |   |
           |      |   (7) ...to here
           |   54 |   if (fd == -1) {
           |      |      ~
           |      |      |
           |      |      (8) following 'false' branch...
           |......
           |   59 |   len = strlen (key);
           |      |   ~~~
           |      |   |
           |      |   (9) ...to here
           |   60 |   if (xwrite (fd, key, len) == -1) {
           |      |      ~
           |      |      |
           |      |      (10) following 'false' branch...
           |......
           |   66 |   if (close (fd) == -1) {
           |      |   ~~ ~
           |      |   |  |
           |      |   |  (12) following 'false' branch...
           |      |   (11) ...to here
           |
         'write_key_to_temp': event 13
           |
           |cc1:
           | (13): ...to here
           |
    <------+
    |
  'do_luks_add_key': events 14-17
    |
    |  146 |   char *keyfile = write_key_to_temp (key);
    |      |                   ^~~~~~~~~~~~~~~~~~~~~~~
    |      |                   |
    |      |                   (14) returning to 'do_luks_add_key' from 'write_key_to_temp'
    |  147 |   if (!keyfile)
    |      |      ~
    |      |      |
    |      |      (15) following 'false' branch...
    |......
    |  150 |   char *newkeyfile = write_key_to_temp (newkey);
    |      |   ~~~~               ~~~~~~~~~~~~~~~~~~~~~~~~~~
    |      |   |                  |
    |      |   |                  (17) calling 'write_key_to_temp' from 'do_luks_add_key'
    |      |   (16) ...to here
    |
    +--> 'write_key_to_temp': events 18-26
           |
           |   41 | write_key_to_temp (const char *key)
           |      | ^~~~~~~~~~~~~~~~~
           |      | |
           |      | (18) entry to 'write_key_to_temp'
           |......
           |   47 |   tempfile = strdup ("/tmp/luksXXXXXX");
           |      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~
           |      |              |
           |      |              (19) allocated here
           |   48 |   if (!tempfile) {
           |      |      ~
           |      |      |
           |      |      (20) following 'false' branch (when 'tempfile_14' is non-NULL)...
           |......
           |   53 |   fd = mkstemp (tempfile);
           |      |   ~~
           |      |   |
           |      |   (21) ...to here
           |   54 |   if (fd == -1) {
           |      |      ~
           |      |      |
           |      |      (22) following 'false' branch...
           |......
           |   59 |   len = strlen (key);
           |      |   ~~~
           |      |   |
           |      |   (23) ...to here
           |   60 |   if (xwrite (fd, key, len) == -1) {
           |      |      ~
           |      |      |
           |      |      (24) following 'false' branch...
           |......
           |   66 |   if (close (fd) == -1) {
           |      |   ~~ ~
           |      |   |  |
           |      |   |  (26) following 'false' branch...
           |      |   (25) ...to here
           |
         'write_key_to_temp': event 27
           |
           |cc1:
           | (27): ...to here
           |
    <------+
    |
  'do_luks_add_key': events 28-32
    |
    |   84 |   free (tempfile);
    |      |   ~~~~~~~~~~~~~~~
    |      |   |
    |      |   (31) first 'free' here
    |      |   (32) second 'free' here; first 'free' was at (31)
    |......
    |  150 |   char *newkeyfile = write_key_to_temp (newkey);
    |      |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
    |      |                      |
    |      |                      (28) returning to 'do_luks_add_key' from 'write_key_to_temp'
    |  151 |   if (!newkeyfile) {
    |      |      ~
    |      |      |
    |      |      (29) following 'false' branch...
    |......
    |  156 |   const char *argv[MAX_ARGS];
    |      |   ~~~~~
    |      |   |
    |      |   (30) ...to here
    |
cc1: all warnings being treated as errors
---
 daemon/luks.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/daemon/luks.c b/daemon/luks.c
index 166cc953a..9d120b0eb 100644
--- a/daemon/luks.c
+++ b/daemon/luks.c
@@ -77,12 +77,15 @@ write_key_to_temp (const char *key)
 }
 #pragma GCC diagnostic pop
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wanalyzer-double-free"
 static void
 remove_temp (char *tempfile)
 {
   unlink (tempfile);
   free (tempfile);
 }
+#pragma GCC diagnostic pop
 
 static int
 luks_format (const char *device, const char *key, int keyslot,