Patch "metag/usercopy: Add early abort to copy_to_user" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    metag/usercopy: Add early abort to copy_to_user

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     metag-usercopy-add-early-abort-to-copy_to_user.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From fb8ea062a8f2e85256e13f55696c5c5f0dfdcc8b Mon Sep 17 00:00:00 2001
From: James Hogan <james.hogan@imgtec.com>
Date: Fri, 31 Mar 2017 13:35:01 +0100
Subject: metag/usercopy: Add early abort to copy_to_user

From: James Hogan <james.hogan@imgtec.com>

commit fb8ea062a8f2e85256e13f55696c5c5f0dfdcc8b upstream.

When copying to userland on Meta, if any faults are encountered
immediately abort the copy instead of continuing on and repeatedly
faulting, and worse potentially copying further bytes successfully to
subsequent valid pages.

Fixes: 373cd784d0fc ("metag: Memory handling")
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-metag@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/metag/lib/usercopy.c |   20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

--- a/arch/metag/lib/usercopy.c
+++ b/arch/metag/lib/usercopy.c
@@ -538,23 +538,31 @@ unsigned long __copy_user(void __user *p
 	if ((unsigned long) src & 1) {
 		__asm_copy_to_user_1(dst, src, retn);
 		n--;
+		if (retn)
+			return retn + n;
 	}
 	if ((unsigned long) dst & 1) {
 		/* Worst case - byte copy */
 		while (n > 0) {
 			__asm_copy_to_user_1(dst, src, retn);
 			n--;
+			if (retn)
+				return retn + n;
 		}
 	}
 	if (((unsigned long) src & 2) && n >= 2) {
 		__asm_copy_to_user_2(dst, src, retn);
 		n -= 2;
+		if (retn)
+			return retn + n;
 	}
 	if ((unsigned long) dst & 2) {
 		/* Second worst case - word copy */
 		while (n >= 2) {
 			__asm_copy_to_user_2(dst, src, retn);
 			n -= 2;
+			if (retn)
+				return retn + n;
 		}
 	}
 
@@ -569,6 +577,8 @@ unsigned long __copy_user(void __user *p
 		while (n >= 8) {
 			__asm_copy_to_user_8x64(dst, src, retn);
 			n -= 8;
+			if (retn)
+				return retn + n;
 		}
 	}
 	if (n >= RAPF_MIN_BUF_SIZE) {
@@ -581,6 +591,8 @@ unsigned long __copy_user(void __user *p
 		while (n >= 8) {
 			__asm_copy_to_user_8x64(dst, src, retn);
 			n -= 8;
+			if (retn)
+				return retn + n;
 		}
 	}
 #endif
@@ -588,11 +600,15 @@ unsigned long __copy_user(void __user *p
 	while (n >= 16) {
 		__asm_copy_to_user_16(dst, src, retn);
 		n -= 16;
+		if (retn)
+			return retn + n;
 	}
 
 	while (n >= 4) {
 		__asm_copy_to_user_4(dst, src, retn);
 		n -= 4;
+		if (retn)
+			return retn + n;
 	}
 
 	switch (n) {
@@ -609,6 +625,10 @@ unsigned long __copy_user(void __user *p
 		break;
 	}
 
+	/*
+	 * If we get here, retn correctly reflects the number of failing
+	 * bytes.
+	 */
 	return retn;
 }
 EXPORT_SYMBOL(__copy_user);


Patches currently in stable-queue which might be from james.hogan@imgtec.com are

queue-4.4/mips-end-spinlocks-with-.insn.patch
queue-4.4/metag-usercopy-add-missing-fixups.patch
queue-4.4/metag-usercopy-add-early-abort-to-copy_to_user.patch
queue-4.4/mips-ralink-fix-typos-in-rt3883-pinctrl.patch
queue-4.4/metag-usercopy-set-flags-before-addz.patch
queue-4.4/metag-usercopy-fix-src-fixup-in-from-user-rapf-loops.patch
queue-4.4/metag-usercopy-drop-unused-macros.patch
queue-4.4/mips-lantiq-fix-missing-xbar-kernel-panic.patch
queue-4.4/metag-usercopy-zero-rest-of-buffer-from-copy_from_user.patch
queue-4.4/metag-usercopy-fix-alignment-error-checking.patch
queue-4.4/mips-force-o32-fp64-support-on-32bit-mips64r6-kernels.patch