From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46861) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cWkwm-0001v3-JV for qemu-devel@nongnu.org; Thu, 26 Jan 2017 09:22:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cWkwj-0006pw-FS for qemu-devel@nongnu.org; Thu, 26 Jan 2017 09:22:44 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53434) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cWkwj-0006la-9k for qemu-devel@nongnu.org; Thu, 26 Jan 2017 09:22:41 -0500 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 7482AC04B302 for ; Thu, 26 Jan 2017 14:22:40 +0000 (UTC) From: Ladi Prosek Date: Thu, 26 Jan 2017 15:22:37 +0100 Message-Id: <1485440557-10384-1-git-send-email-lprosek@redhat.com> Subject: [Qemu-devel] [PATCH] memory: don't sign-extend 32-bit writes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: pbonzini@redhat.com ldl_p has a signed return type so assigning it to uint64_t implicitly sign-extends the value. This results in devices with min_access_size = 8 seeing unexpected values passed to their write handlers. Example: guest performs a 32-bit write of 0x80000000 to an mmio region and the handler receives 0xFFFFFFFF80000000 in its value argument. Signed-off-by: Ladi Prosek --- exec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/exec.c b/exec.c index f2bed92..b05c5d2 100644 --- a/exec.c +++ b/exec.c @@ -2630,7 +2630,7 @@ static MemTxResult address_space_write_continue(AddressSpace *as, hwaddr addr, break; case 4: /* 32 bit write access */ - val = ldl_p(buf); + val = (uint32_t)ldl_p(buf); result |= memory_region_dispatch_write(mr, addr1, val, 4, attrs); break; -- 2.7.4