From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56077) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fSQYa-00079F-Oi for qemu-devel@nongnu.org; Mon, 11 Jun 2018 13:24:41 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fSQYa-0000m9-09 for qemu-devel@nongnu.org; Mon, 11 Jun 2018 13:24:40 -0400 Received: from orth.archaic.org.uk ([2001:8b0:1d0::2]:42702) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fSQYZ-0000kf-PF for qemu-devel@nongnu.org; Mon, 11 Jun 2018 13:24:39 -0400 From: Peter Maydell Date: Mon, 11 Jun 2018 18:10:06 +0100 Message-Id: <20180611171007.4165-3-peter.maydell@linaro.org> In-Reply-To: <20180611171007.4165-1-peter.maydell@linaro.org> References: <20180611171007.4165-1-peter.maydell@linaro.org> Subject: [Qemu-devel] [PATCH 2/3] exec.c: Don't accidentally sign-extend 4-byte loads in subpage_read() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: patches@linaro.org, Richard Henderson , Paolo Bonzini In subpage_read() we perform a load of the data into a local buffer which we then access using ldub_p(), lduw_p(), ldl_p() or ldq_p() depending on its size, storing the result into the uint64_t *data. Since ldl_p() returns an 'int', this means that for the 4-byte case we will sign-extend the data, whereas for 1 and 2 byte reads we zero-extend it. This ought not to matter since the caller will likely ignore values in the high bytes of the data, but add a cast so that we're consistent. Signed-off-by: Peter Maydell --- exec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/exec.c b/exec.c index 9cbba6adcd3..90b47cde7b1 100644 --- a/exec.c +++ b/exec.c @@ -2747,7 +2747,7 @@ static MemTxResult subpage_read(void *opaque, hwaddr addr, uint64_t *data, *data = lduw_p(buf); return MEMTX_OK; case 4: - *data = ldl_p(buf); + *data = (uint32_t)ldl_p(buf); return MEMTX_OK; case 8: *data = ldq_p(buf); -- 2.17.1