X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=probes%2Flttng-probe-user.c;h=099a66b229a46fcc90f7b5fd7e504a3806d7d0e6;hb=140a62b06d149c780aef54f6ef0282310407734c;hp=d0b5cf297367ce3c209b69ecb491e969ec321270;hpb=2a8b83a12300795c2f82ba19826e2eeaa5135030;p=lttng-modules.git

diff --git a/probes/lttng-probe-user.c b/probes/lttng-probe-user.c
index d0b5cf29..099a66b2 100644
--- a/probes/lttng-probe-user.c
+++ b/probes/lttng-probe-user.c
@@ -19,7 +19,8 @@
  */
 
 #include <linux/uaccess.h>
-#include "lttng-probe-user.h"
+#include <linux/module.h>
+#include <probes/lttng-probe-user.h>
 
 /*
  * Calculate string length. Include final null terminating character if there is
@@ -30,14 +31,22 @@
 long lttng_strlen_user_inatomic(const char *addr)
 {
 	long count = 0;
-	mm_segment_t old_fs = get_fs();
+	mm_segment_t old_fs;
 
+	if (!addr)
+		return 0;
+
+	old_fs = get_fs();
 	set_fs(KERNEL_DS);
 	pagefault_disable();
 	for (;;) {
 		char v;
 		unsigned long ret;
 
+		if (unlikely(!access_ok(VERIFY_READ,
+				(__force const char __user *) addr,
+				sizeof(v))))
+			break;
 		ret = __copy_from_user_inatomic(&v,
 			(__force const char __user *)(addr),
 			sizeof(v));
@@ -52,3 +61,4 @@ long lttng_strlen_user_inatomic(const char *addr)
 	set_fs(old_fs);
 	return count;
 }
+EXPORT_SYMBOL_GPL(lttng_strlen_user_inatomic);