depends on MCOUNT
default y
+config DEBUG_STRICT_USER_COPY_CHECKS
+ bool "Strict copy size checks"
+ depends on DEBUG_KERNEL && !TRACE_BRANCH_PROFILING
+ ---help---
+ Enabling this option turns a certain set of sanity checks for user
+ copy operations into compile time failures.
+
+ The copy_from_user() etc checks are there to help test if there
+ are sufficient security checks on the length argument of
+ the copy operation, by having gcc prove that the argument is
+ within bounds.
+
+ If unsure, or if you run an older (pre 4.4) gcc, say N.
+
endmenu
return __copy_user(to, (__force void __user *) from, n);
}
+extern void copy_from_user_overflow(void)
+#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
+ __compiletime_error("copy_from_user() buffer size is not provably correct")
+#else
+ __compiletime_warning("copy_from_user() buffer size is not provably correct")
+#endif
+;
+
static inline unsigned long copy_from_user(void *to, const void __user *from, unsigned long n)
{
+ int sz = __compiletime_object_size(to);
+
+ if (unlikely(sz != -1 && sz < n)) {
+ copy_from_user_overflow();
+ return -EFAULT;
+ }
+
if (n && __access_ok((unsigned long) from, n))
return __copy_user((__force void __user *) to, from, n);
else
*/
#ifdef __KERNEL__
+#include <linux/errno.h>
#include <linux/compiler.h>
#include <linux/string.h>
#include <linux/thread_info.h>
extern int __get_user_bad(void);
+extern void copy_from_user_overflow(void)
+#ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
+ __compiletime_error("copy_from_user() buffer size is not provably correct")
+#else
+ __compiletime_warning("copy_from_user() buffer size is not provably correct")
+#endif
+;
+
extern unsigned long __must_check ___copy_from_user(void *to,
const void __user *from,
unsigned long size);
static inline unsigned long __must_check
copy_from_user(void *to, const void __user *from, unsigned long size)
{
- unsigned long ret = ___copy_from_user(to, from, size);
-
- if (unlikely(ret))
- ret = copy_from_user_fixup(to, from, size);
+ unsigned long ret = (unsigned long) -EFAULT;
+ int sz = __compiletime_object_size(to);
+
+ if (likely(sz == -1 || sz >= size)) {
+ ret = ___copy_from_user(to, from, size);
+ if (unlikely(ret))
+ ret = copy_from_user_fixup(to, from, size);
+ } else {
+ copy_from_user_overflow();
+ }
return ret;
}
#define __copy_from_user copy_from_user
obj-$(CONFIG_SPARC32) += atomic32.o
obj-y += ksyms.o
obj-$(CONFIG_SPARC64) += PeeCeeI.o
+obj-y += usercopy.o
--- /dev/null
+#include <linux/module.h>
+#include <linux/bug.h>
+
+void copy_from_user_overflow(void)
+{
+ WARN(1, "Buffer overflow detected!\n");
+}
+EXPORT_SYMBOL(copy_from_user_overflow);