X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=probes%2Flttng-probe-user.c;h=c11e1e0f3b920779fa3466fa801219937e8e0ecf;hb=39192dfbea6041eefea1676c554ba73946793c71;hp=d0b5cf297367ce3c209b69ecb491e969ec321270;hpb=2a8b83a12300795c2f82ba19826e2eeaa5135030;p=lttng-modules.git

diff --git a/probes/lttng-probe-user.c b/probes/lttng-probe-user.c
index d0b5cf29..c11e1e0f 100644
--- a/probes/lttng-probe-user.c
+++ b/probes/lttng-probe-user.c
@@ -1,25 +1,16 @@
-/*
+/* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
+ *
  * lttng-probe-user.c
  *
  * Copyright (C) 2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include <linux/uaccess.h>
-#include "lttng-probe-user.h"
+#include <linux/module.h>
+#include <wrapper/uaccess.h>
+#include <probes/lttng-probe-user.h>
+
+#define LTTNG_MAX_USER_STRING_LEN 1048576 /* 1MB */
 
 /*
  * Calculate string length. Include final null terminating character if there is
@@ -30,25 +21,32 @@
 long lttng_strlen_user_inatomic(const char *addr)
 {
 	long count = 0;
-	mm_segment_t old_fs = get_fs();
 
-	set_fs(KERNEL_DS);
+	if (!addr)
+		return 0;
+
 	pagefault_disable();
 	for (;;) {
 		char v;
 		unsigned long ret;
 
+		if (unlikely(!lttng_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));
 		if (unlikely(ret > 0))
 			break;
 		count++;
+		if (unlikely(count > LTTNG_MAX_USER_STRING_LEN))
+			break;
 		if (unlikely(!v))
 			break;
 		addr++;
 	}
 	pagefault_enable();
-	set_fs(old_fs);
 	return count;
 }
+EXPORT_SYMBOL_GPL(lttng_strlen_user_inatomic);