Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull more misc uaccess and vfs updates from Al Viro:
 "The rest of the stuff from -next (more uaccess work) + assorted fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  score: traps: Add missing include file to fix build error
  fs/super.c: don't fool lockdep in freeze_super() and thaw_super() paths
  fs/super.c: fix race between freeze_super() and thaw_super()
  overlayfs: Fix setting IOP_XATTR flag
  iov_iter: kernel-doc import_iovec() and rw_copy_check_uvector()
  blackfin: no access_ok() for __copy_{to,from}_user()
  arm64: don't zero in __copy_from_user{,_inatomic}
  arm: don't zero in __copy_from_user_inatomic()/__copy_from_user()
  arc: don't leak bits of kernel stack into coredump
  alpha: get rid of tail-zeroing in __copy_user()

10 files changed, 48 insertions, 78 deletions

diff --git a/arch/alpha/include/asm/uaccess.h b/arch/alpha/include/asm/uaccess.h
index 466e42e96bfa..94f587535dee 100644
--- a/arch/alpha/include/asm/uaccess.h
+++ b/arch/alpha/include/asm/uaccess.h
@@ -396,11 +396,12 @@ copy_to_user(void __user *to, const void *from, long n)
 extern inline long
 copy_from_user(void *to, const void __user *from, long n)
 {
+	long res = n;
 	if (likely(__access_ok((unsigned long)from, n, get_fs())))
-		n = __copy_tofrom_user_nocheck(to, (__force void *)from, n);
-	else
-		memset(to, 0, n);
-	return n;
+		res = __copy_from_user_inatomic(to, from, n);
+	if (unlikely(res))
+		memset(to + (n - res), 0, res);
+	return res;
 }
 
 extern void __do_clear_user(void);
diff --git a/arch/alpha/lib/copy_user.S b/arch/alpha/lib/copy_user.S
index 2238068b1b40..509f62b65311 100644
--- a/arch/alpha/lib/copy_user.S
+++ b/arch/alpha/lib/copy_user.S
@@ -126,22 +126,8 @@ $65:
 	bis $31,$31,$0
 $41:
 $35:
-$exitout:
-	ret $31,($28),1
-
 $exitin:
-	/* A stupid byte-by-byte zeroing of the rest of the output
-	   buffer.  This cures security holes by never leaving 
-	   random kernel data around to be copied elsewhere.  */
-
-	mov $0,$1
-$101:
-	EXO ( ldq_u $2,0($6) )
-	subq $1,1,$1
-	mskbl $2,$6,$2
-	EXO ( stq_u $2,0($6) )
-	addq $6,1,$6
-	bgt $1,$101
+$exitout:
 	ret $31,($28),1
 
 	.end __copy_user
diff --git a/arch/alpha/lib/ev6-copy_user.S b/arch/alpha/lib/ev6-copy_user.S
index debcc3b6b704..be720b518af9 100644
--- a/arch/alpha/lib/ev6-copy_user.S
+++ b/arch/alpha/lib/ev6-copy_user.S
@@ -228,33 +228,12 @@ $dirtyentry:
 	bgt $0,$onebyteloop	# U  .. .. ..	: U L U L
 
 $zerolength:
+$exitin:
 $exitout:			# Destination for exception recovery(?)
 	nop			# .. .. .. E
 	nop			# .. .. E  ..
 	nop			# .. E  .. ..
 	ret $31,($28),1		# L0 .. .. ..	: L U L U
 
-$exitin:
-
-	/* A stupid byte-by-byte zeroing of the rest of the output
-	   buffer.  This cures security holes by never leaving 
-	   random kernel data around to be copied elsewhere.  */
-
-	nop
-	nop
-	nop
-	mov	$0,$1
-
-$101:
-	EXO ( stb $31,0($6) )	# L
-	subq $1,1,$1		# E
-	addq $6,1,$6		# E
-	bgt $1,$101		# U
-
-	nop
-	nop
-	nop
-	ret $31,($28),1		# L0
-
 	.end __copy_user
 	EXPORT_SYMBOL(__copy_user)
diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
index 6cb3736b6b83..d347bbc086fe 100644
--- a/arch/arc/kernel/signal.c
+++ b/arch/arc/kernel/signal.c
@@ -107,13 +107,13 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
 	struct user_regs_struct uregs;
 
 	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
-	if (!err)
-		set_current_blocked(&set);
-
 	err |= __copy_from_user(&uregs.scratch,
 				&(sf->uc.uc_mcontext.regs.scratch),
 				sizeof(sf->uc.uc_mcontext.regs.scratch));
+	if (err)
+		return err;
 
+	set_current_blocked(&set);
 	regs->bta	= uregs.scratch.bta;
 	regs->lp_start	= uregs.scratch.lp_start;
 	regs->lp_end	= uregs.scratch.lp_end;
@@ -138,7 +138,7 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
 	regs->r0	= uregs.scratch.r0;
 	regs->sp	= uregs.scratch.sp;
 
-	return err;
+	return 0;
 }
 
 static inline int is_do_ss_needed(unsigned int magic)
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index a93c0f99acf7..1f59ea051bab 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -533,11 +533,12 @@ __clear_user(void __user *addr, unsigned long n)
 
 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-	if (access_ok(VERIFY_READ, from, n))
-		n = __copy_from_user(to, from, n);
-	else /* security hole - plug it */
-		memset(to, 0, n);
-	return n;
+	unsigned long res = n;
+	if (likely(access_ok(VERIFY_READ, from, n)))
+		res = __copy_from_user(to, from, n);
+	if (unlikely(res))
+		memset(to + (n - res), 0, res);
+	return res;
 }
 
 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
diff --git a/arch/arm/lib/copy_from_user.S b/arch/arm/lib/copy_from_user.S
index f549c57ea435..63e4c1ed0225 100644
--- a/arch/arm/lib/copy_from_user.S
+++ b/arch/arm/lib/copy_from_user.S
@@ -100,12 +100,9 @@ EXPORT_SYMBOL(arm_copy_from_user)
 	.pushsection .fixup,"ax"
 	.align 0
 	copy_abort_preamble
-	ldmfd	sp!, {r1, r2}
-	sub	r3, r0, r1
-	rsb	r1, r3, r2
-	str	r1, [sp]
-	bl	__memzero
-	ldr	r0, [sp], #4
+	ldmfd	sp!, {r1, r2, r3}
+	sub	r0, r0, r1
+	rsb	r0, r0, r2
 	copy_abort_end
 	.popsection
 
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index c47257c91b77..bcaf6fba1b65 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -278,14 +278,16 @@ static inline unsigned long __must_check __copy_to_user(void __user *to, const v
 
 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n)
 {
+	unsigned long res = n;
 	kasan_check_write(to, n);
 
 	if (access_ok(VERIFY_READ, from, n)) {
 		check_object_size(to, n, false);
-		n = __arch_copy_from_user(to, from, n);
-	} else /* security hole - plug it */
-		memset(to, 0, n);
-	return n;
+		res = __arch_copy_from_user(to, from, n);
+	}
+	if (unlikely(res))
+		memset(to + (n - res), 0, res);
+	return res;
 }
 
 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n)
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 0b90497d4424..4fd67ea03bb0 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -79,11 +79,6 @@ ENDPROC(__arch_copy_from_user)
 
 	.section .fixup,"ax"
 	.align	2
-9998:
-	sub	x0, end, dst
-9999:
-	strb	wzr, [dst], #1			// zero remaining buffer space
-	cmp	dst, end
-	b.lo	9999b
+9998:	sub	x0, end, dst			// bytes not copied
 	ret
 	.previous
diff --git a/arch/blackfin/include/asm/uaccess.h b/arch/blackfin/include/asm/uaccess.h
index 0a2a70096d8b..0eff88aa6d6a 100644
--- a/arch/blackfin/include/asm/uaccess.h
+++ b/arch/blackfin/include/asm/uaccess.h
@@ -163,18 +163,29 @@ static inline int bad_user_access_length(void)
 		: "a" (__ptr(ptr)));		\
 })
 
-#define __copy_from_user(to, from, n) copy_from_user(to, from, n)
-#define __copy_to_user(to, from, n) copy_to_user(to, from, n)
 #define __copy_to_user_inatomic __copy_to_user
 #define __copy_from_user_inatomic __copy_from_user
 
 static inline unsigned long __must_check
+__copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+	memcpy(to, (const void __force *)from, n);
+	return 0;
+}
+
+static inline unsigned long __must_check
+__copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+	memcpy((void __force *)to, from, n);
+	SSYNC();
+	return 0;
+}
+
+static inline unsigned long __must_check
 copy_from_user(void *to, const void __user *from, unsigned long n)
 {
-	if (likely(access_ok(VERIFY_READ, from, n))) {
-		memcpy(to, (const void __force *)from, n);
-		return 0;
-	}
+	if (likely(access_ok(VERIFY_READ, from, n)))
+		return __copy_from_user(to, from, n);
 	memset(to, 0, n);
 	return n;
 }
@@ -182,12 +193,9 @@ copy_from_user(void *to, const void __user *from, unsigned long n)
 static inline unsigned long __must_check
 copy_to_user(void __user *to, const void *from, unsigned long n)
 {
-	if (access_ok(VERIFY_WRITE, to, n))
-		memcpy((void __force *)to, from, n);
-	else
-		return n;
-	SSYNC();
-	return 0;
+	if (likely(access_ok(VERIFY_WRITE, to, n)))
+		return __copy_to_user(to, from, n);
+	return n;
 }
 
 /*
diff --git a/arch/score/kernel/traps.c b/arch/score/kernel/traps.c
index 1517a7dcd6d9..5cea1e750cec 100644
--- a/arch/score/kernel/traps.c
+++ b/arch/score/kernel/traps.c
@@ -29,6 +29,7 @@
 #include <asm/cacheflush.h>
 #include <asm/irq.h>
 #include <asm/irq_regs.h>
+#include <asm/uaccess.h>
 
 unsigned long exception_handlers[32];