Merge tag 'asm-generic-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

Pull asm-generic updates from Arnd Bergmann:
 "The main content for 5.15 is a series that cleans up the handling of
  strncpy_from_user() and strnlen_user(), removing a lot of slightly
  incorrect versions of these in favor of the lib/strn*.c helpers that
  implement these correctly and more efficiently.

  The only architectures that retain a private version now are mips,
  ia64, um and parisc. I had offered to convert those at all, but Thomas
  Bogendoerfer wanted to keep the mips version for the moment until he
  had a chance to do regression testing.

  The branch also contains two patches for bitops and for ffs()"

* tag 'asm-generic-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  bitops/non-atomic: make @nr unsigned to avoid any DIV
  asm-generic: ffs: Drop bogus reference to ffz location
  asm-generic: reverse GENERIC_{STRNCPY_FROM,STRNLEN}_USER symbols
  asm-generic: remove extra strn{cpy_from,len}_user declarations
  asm-generic: uaccess: remove inline strncpy_from_user/strnlen_user
  s390: use generic strncpy/strnlen from_user
  microblaze: use generic strncpy/strnlen from_user
  csky: use generic strncpy/strnlen from_user
  arc: use generic strncpy/strnlen from_user
  hexagon: use generic strncpy/strnlen from_user
  h8300: remove stale strncpy_from_user
  asm-generic/uaccess.h: remove __strncpy_from_user/__strnlen_user

3 files changed, 13 insertions, 8 deletions

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 0561b73cfd9a..77e66d3719f6 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -7,6 +7,8 @@ config UML
 	default y
 	select ARCH_EPHEMERAL_INODES
 	select ARCH_HAS_KCOV
+	select ARCH_HAS_STRNCPY_FROM_USER
+	select ARCH_HAS_STRNLEN_USER
 	select ARCH_NO_PREEMPT
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_SECCOMP_FILTER
diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h
index fe66d659acad..191ef36dd543 100644
--- a/arch/um/include/asm/uaccess.h
+++ b/arch/um/include/asm/uaccess.h
@@ -23,16 +23,13 @@
 
 extern unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n);
 extern unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n);
-extern long __strncpy_from_user(char *dst, const char __user *src, long count);
-extern long __strnlen_user(const void __user *str, long len);
 extern unsigned long __clear_user(void __user *mem, unsigned long len);
 static inline int __access_ok(unsigned long addr, unsigned long size);
 
 /* Teach asm-generic/uaccess.h that we have C functions for these. */
 #define __access_ok __access_ok
 #define __clear_user __clear_user
-#define __strnlen_user __strnlen_user
-#define __strncpy_from_user __strncpy_from_user
+
 #define INLINE_COPY_FROM_USER
 #define INLINE_COPY_TO_USER
 
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index 6c76df96e858..a509be911026 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -189,11 +189,14 @@ static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
 	return 0;
 }
 
-long __strncpy_from_user(char *dst, const char __user *src, long count)
+long strncpy_from_user(char *dst, const char __user *src, long count)
 {
 	long n;
 	char *ptr = dst;
 
+	if (!access_ok(src, 1))
+		return -EFAULT;
+
 	if (uaccess_kernel()) {
 		strncpy(dst, (__force void *) src, count);
 		return strnlen(dst, count);
@@ -205,7 +208,7 @@ long __strncpy_from_user(char *dst, const char __user *src, long count)
 		return -EFAULT;
 	return strnlen(dst, count);
 }
-EXPORT_SYMBOL(__strncpy_from_user);
+EXPORT_SYMBOL(strncpy_from_user);
 
 static int clear_chunk(unsigned long addr, int len, void *unused)
 {
@@ -236,10 +239,13 @@ static int strnlen_chunk(unsigned long str, int len, void *arg)
 	return 0;
 }
 
-long __strnlen_user(const void __user *str, long len)
+long strnlen_user(const char __user *str, long len)
 {
 	int count = 0, n;
 
+	if (!access_ok(str, 1))
+		return -EFAULT;
+
 	if (uaccess_kernel())
 		return strnlen((__force char*)str, len) + 1;
 
@@ -248,7 +254,7 @@ long __strnlen_user(const void __user *str, long len)
 		return count + 1;
 	return 0;
 }
-EXPORT_SYMBOL(__strnlen_user);
+EXPORT_SYMBOL(strnlen_user);
 
 /**
  * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant