Fix: Deference after null check in sessiond set_option

Found by Coverity:

2. var_compare_op: Comparing arg to null implies that arg might be null.

CID 1256137 (#1 of 9): Dereference after null check (FORWARD_NULL)14.
var_deref_model: Passing null pointer arg to strdup, which dereferences
it.

[... same for #2 through #9 ]

This should not really be an issue since
1) options that use the "arg" parameter will not be set by popt if one
   is not provided,
2) the configuration file parser will never invoke set_option with
   a NULL argument; if no "value" is provided in the file, an empty
   string is passed.

The second point is the reason for the "arg && arg[0] == '\0'" check;
we already know that the argument is invalid since an empty string
is never a valid argument for the supported options.

Nonetheless, it makes sense for Coverity to flag this and moving
the check to individual cases, although very verbose, is clear.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 92899873baebd743c5de265f795b41ae00f22498..cd283524cf542d93f442e6a3d486558bac66eff3 100644 (file)
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -4580,18 +4580,11 @@ static int set_option(int opt, const char *arg, const char *optname)
 {
        int ret = 0;
 
-       if (arg && arg[0] == '\0') {
-               /*
-                * This only happens if the value is read from daemon config
-                * file. This means the option requires an argument and the
-                * configuration file contains a line such as:
-                * my_option =
-                */
-               ret = -EINVAL;
-               goto end;
-       }
-
        if (string_match(optname, "client-sock") || opt == 'c') {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-c, --client-sock");
@@ -4599,6 +4592,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        snprintf(client_unix_sock_path, PATH_MAX, "%s", arg);
                }
        } else if (string_match(optname, "apps-sock") || opt == 'a') {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-a, --apps-sock");
@@ -4610,6 +4607,10 @@ static int set_option(int opt, const char *arg, const char *optname)
        } else if (string_match(optname, "background") || opt == 'b') {
                opt_background = 1;
        } else if (string_match(optname, "group") || opt == 'g') {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-g, --group");
@@ -4638,6 +4639,10 @@ static int set_option(int opt, const char *arg, const char *optname)
        } else if (string_match(optname, "sig-parent") || opt == 'S') {
                opt_sig_parent = 1;
        } else if (string_match(optname, "kconsumerd-err-sock")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--kconsumerd-err-sock");
@@ -4645,6 +4650,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        snprintf(kconsumer_data.err_unix_sock_path, PATH_MAX, "%s", arg);
                }
        } else if (string_match(optname, "kconsumerd-cmd-sock")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--kconsumerd-cmd-sock");
@@ -4652,6 +4661,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        snprintf(kconsumer_data.cmd_unix_sock_path, PATH_MAX, "%s", arg);
                }
        } else if (string_match(optname, "ustconsumerd64-err-sock")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--ustconsumerd64-err-sock");
@@ -4659,6 +4672,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        snprintf(ustconsumer64_data.err_unix_sock_path, PATH_MAX, "%s", arg);
                }
        } else if (string_match(optname, "ustconsumerd64-cmd-sock")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--ustconsumerd64-cmd-sock");
@@ -4666,6 +4683,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        snprintf(ustconsumer64_data.cmd_unix_sock_path, PATH_MAX, "%s", arg);
                }
        } else if (string_match(optname, "ustconsumerd32-err-sock")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--ustconsumerd32-err-sock");
@@ -4673,6 +4694,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        snprintf(ustconsumer32_data.err_unix_sock_path, PATH_MAX, "%s", arg);
                }
        } else if (string_match(optname, "ustconsumerd32-cmd-sock")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--ustconsumerd32-cmd-sock");
@@ -4702,6 +4727,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        opt_verbose_consumer += 1;
                }
        } else if (string_match(optname, "consumerd32-path")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--consumerd32-path");
@@ -4717,6 +4746,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        consumerd32_bin_override = 1;
                }
        } else if (string_match(optname, "consumerd32-libdir")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--consumerd32-libdir");
@@ -4732,6 +4765,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        consumerd32_libdir_override = 1;
                }
        } else if (string_match(optname, "consumerd64-path")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--consumerd64-path");
@@ -4747,6 +4784,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        consumerd64_bin_override = 1;
                }
        } else if (string_match(optname, "consumerd64-libdir")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--consumerd64-libdir");
@@ -4762,6 +4803,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        consumerd64_libdir_override = 1;
                }
        } else if (string_match(optname, "pidfile") || opt == 'p') {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-p, --pidfile");
@@ -4774,6 +4819,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        }
                }
        } else if (string_match(optname, "agent-tcp-port")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--agent-tcp-port");
@@ -4798,6 +4847,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        DBG3("Agent TCP port set to non default: %u", agent_tcp_port);
                }
        } else if (string_match(optname, "load") || opt == 'l') {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-l, --load");
@@ -4810,6 +4863,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        }
                }
        } else if (string_match(optname, "kmod-probes")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--kmod-probes");
@@ -4822,6 +4879,10 @@ static int set_option(int opt, const char *arg, const char *optname)
                        }
                }
        } else if (string_match(optname, "extra-kmod-probes")) {
+               if (!arg || *arg == '\0') {
+                       ret = -EINVAL;
+                       goto end;
+               }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--extra-kmod-probes");