From mboxrd@z Thu Jan 1 00:00:00 1970 From: Willy Tarreau Subject: [PATCH 3.10 202/250] metag/usercopy: Fix alignment error checking Date: Thu, 8 Jun 2017 00:59:48 +0200 Message-ID: <1496876436-32402-203-git-send-email-w@1wt.eu> References: <1496876436-32402-1-git-send-email-w@1wt.eu> Return-path: In-Reply-To: <1496876436-32402-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: James Hogan , linux-metag@vger.kernel.org, Jiri Slaby , Willy Tarreau From: James Hogan 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 Cc: linux-metag@vger.kernel.org Signed-off-by: Jiri Slaby Signed-off-by: Willy Tarreau --- arch/metag/lib/usercopy.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/arch/metag/lib/usercopy.c b/arch/metag/lib/usercopy.c index b3ebfe9..a26c889 100644 --- a/arch/metag/lib/usercopy.c +++ b/arch/metag/lib/usercopy.c @@ -830,6 +830,8 @@ unsigned long __copy_user_zeroing(void *pdst, const void __user *psrc, 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 */ @@ -843,6 +845,8 @@ unsigned long __copy_user_zeroing(void *pdst, const void __user *psrc, 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 */ @@ -854,12 +858,6 @@ unsigned long __copy_user_zeroing(void *pdst, const void __user *psrc, } } - /* 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)) { -- 2.8.0.rc2.1.gbe9624a