linux-kernel - [PATCH 3.18 118/124] metag/usercopy: Fix alignment error checking

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20170420063601.601198806@linuxfoundation.org>
Date:   Thu, 20 Apr 2017 08:36:33 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, James Hogan <james.hogan@...tec.com>,
        linux-metag@...r.kernel.org
Subject: [PATCH 3.18 118/124] metag/usercopy: Fix alignment error checking

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

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

commit 2257211942bbbf6c798ab70b487d7e62f7835a1a upstream.

Fix the error checking of the alignment adjustment code in
raw_copy_from_user(), which mistakenly considers it safe to skip the
error check when aligning the source buffer on a 2 or 4 byte boundary.

If the destination buffer was unaligned it may have started to copy
using byte or word accesses, which could well be at the start of a new
(valid) source page. This would result in it appearing to have copied 1
or 2 bytes at the end of the first (invalid) page rather than none at
all.

Fixes: 373cd784d0fc ("metag: Memory handling")
Signed-off-by: James Hogan <james.hogan@...tec.com>
Cc: linux-metag@...r.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/metag/lib/usercopy.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

--- a/arch/metag/lib/usercopy.c
+++ b/arch/metag/lib/usercopy.c
@@ -717,6 +717,8 @@ unsigned long __copy_user_zeroing(void *
 	if ((unsigned long) src & 1) {
 		__asm_copy_from_user_1(dst, src, retn);
 		n--;
+		if (retn)
+			goto copy_exception_bytes;
 	}
 	if ((unsigned long) dst & 1) {
 		/* Worst case - byte copy */
@@ -730,6 +732,8 @@ unsigned long __copy_user_zeroing(void *
 	if (((unsigned long) src & 2) && n >= 2) {
 		__asm_copy_from_user_2(dst, src, retn);
 		n -= 2;
+		if (retn)
+			goto copy_exception_bytes;
 	}
 	if ((unsigned long) dst & 2) {
 		/* Second worst case - word copy */
@@ -741,12 +745,6 @@ unsigned long __copy_user_zeroing(void *
 		}
 	}
 
-	/* We only need one check after the unalignment-adjustments,
-	   because if both adjustments were done, either both or
-	   neither reference had an exception.  */
-	if (retn != 0)
-		goto copy_exception_bytes;
-
 #ifdef USE_RAPF
 	/* 64 bit copy loop */
 	if (!(((unsigned long) src | (unsigned long) dst) & 7)) {