lib, uaccess: add failure injection to usercopy functions

To test fault-tolerance of user memory access functions, introduce fault
injection to usercopy functions.

If a failure is expected return either -EFAULT or the total amount of
bytes that were not copied.

Signed-off-by: Albert van der Linde <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Akinobu Mita <[email protected]>
Reviewed-by: Alexander Potapenko <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 14cae2584db4..1635111c5bd2 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -2,6 +2,7 @@
 #include <crypto/hash.h>
 #include <linux/export.h>
 #include <linux/bvec.h>
+#include <linux/fault-inject-usercopy.h>
 #include <linux/uio.h>
 #include <linux/pagemap.h>
 #include <linux/slab.h>
@@ -140,6 +141,8 @@
 
 static int copyout(void __user *to, const void *from, size_t n)
 {
+	if (should_fail_usercopy())
+		return n;
 	if (access_ok(to, n)) {
 		instrument_copy_to_user(to, from, n);
 		n = raw_copy_to_user(to, from, n);
@@ -149,6 +152,8 @@ static int copyout(void __user *to, const void *from, size_t n)
 
 static int copyin(void *to, const void __user *from, size_t n)
 {
+	if (should_fail_usercopy())
+		return n;
 	if (access_ok(from, n)) {
 		instrument_copy_from_user(to, from, n);
 		n = raw_copy_from_user(to, from, n);