X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=probes%2Flttng-probe-user.c;h=c11e1e0f3b920779fa3466fa801219937e8e0ecf;hb=9d72c4911cfca9b17905c1a336fc56eeb6bac5bc;hp=4162a7e42d2d94942fa4d5927afff8f95660d807;hpb=9f36eaed6f91d5897924b551b44d1edd8cee00e2;p=lttng-modules.git

diff --git a/probes/lttng-probe-user.c b/probes/lttng-probe-user.c
index 4162a7e4..c11e1e0f 100644
--- a/probes/lttng-probe-user.c
+++ b/probes/lttng-probe-user.c
@@ -7,8 +7,11 @@
 
 #include <linux/uaccess.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
  * one, or ends at first fault. Disabling page faults ensures that we can safely
@@ -18,19 +21,16 @@
 long lttng_strlen_user_inatomic(const char *addr)
 {
 	long count = 0;
-	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,
+		if (unlikely(!lttng_access_ok(VERIFY_READ,
 				(__force const char __user *) addr,
 				sizeof(v))))
 			break;
@@ -40,12 +40,13 @@ long lttng_strlen_user_inatomic(const char *addr)
 		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);