[lttng-dev] [PATCH lttng-modules] Fix: NULL pointer dereference of THIS_MODULE with built-in modules

[Francis Deslauriers]

THIS MODULE is defined to 0 when a module is built-in the kernel [1].
This caused NULL pointer dereference when booting a kernel with the
lttng-modules built-in.
To fix this issue, add #if guard around the wrapper_lttng_fixup_sig
function checking if the MODULE macro is defined to confirm that this
piece of code will end up in a module and not in the kernel itself.

[1]: linux/include/linux/export.h:32
Fixes: #1107

Signed-off-by: Francis Deslauriers <francis.deslauriers at efficios.com>
---
 wrapper/tracepoint.h | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/wrapper/tracepoint.h b/wrapper/tracepoint.h
index 367cdf4..780f9a8 100644
--- a/wrapper/tracepoint.h
+++ b/wrapper/tracepoint.h
@@ -87,6 +87,10 @@ int wrapper_tracepoint_module_notify(struct notifier_block *nb,
 	}
 }
 
+#endif /* CONFIG_MODULE_SIG */
+
+#if defined(CONFIG_MODULE_SIG) && defined(MODULE)
+
 static inline
 int wrapper_lttng_fixup_sig(struct module *mod)
 {
@@ -106,7 +110,7 @@ int wrapper_lttng_fixup_sig(struct module *mod)
 	return ret;
 }
 
-#else /* CONFIG_MODULE_SIG */
+#else /* #if defined(CONFIG_MODULE_SIG) && defined(MODULE) */
 
 static inline
 int wrapper_lttng_fixup_sig(struct module *mod)
@@ -114,6 +118,6 @@ int wrapper_lttng_fixup_sig(struct module *mod)
 	return 0;
 }
 
-#endif /* #else CONFIG_MODULE_SIG */
+#endif /*#else #if defined(CONFIG_MODULE_SIG) && defined(MODULE) */
 
 #endif /* _LTTNG_WRAPPER_TRACEPOINT_H */
-- 
2.7.4