From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jOgTt-0004CV-2E for linux-um@lists.infradead.org; Wed, 15 Apr 2020 11:45:27 +0000 From: Sasha Levin Subject: [PATCH AUTOSEL 5.4 37/84] um: ubd: Prevent buffer overrun on command completion Date: Wed, 15 Apr 2020 07:43:54 -0400 Message-Id: <20200415114442.14166-37-sashal@kernel.org> In-Reply-To: <20200415114442.14166-1-sashal@kernel.org> References: <20200415114442.14166-1-sashal@kernel.org> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Martyn Welch , Richard Weinberger , linux-um@lists.infradead.org, Gabriel Krisman Bertazi , Sasha Levin From: Gabriel Krisman Bertazi [ Upstream commit 6e682d53fc1ef73a169e2a5300326cb23abb32ee ] On the hypervisor side, when completing commands and the pipe is full, we retry writing only the entries that failed, by offsetting io_req_buffer, but we don't reduce the number of bytes written, which can cause a buffer overrun of io_req_buffer, and write garbage to the pipe. Cc: Martyn Welch Signed-off-by: Gabriel Krisman Bertazi Signed-off-by: Richard Weinberger Signed-off-by: Sasha Levin --- arch/um/drivers/ubd_kern.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c index 6627d7c30f370..0f5d0a699a49b 100644 --- a/arch/um/drivers/ubd_kern.c +++ b/arch/um/drivers/ubd_kern.c @@ -1606,7 +1606,9 @@ int io_thread(void *arg) written = 0; do { - res = os_write_file(kernel_fd, ((char *) io_req_buffer) + written, n); + res = os_write_file(kernel_fd, + ((char *) io_req_buffer) + written, + n - written); if (res >= 0) { written += res; } -- 2.20.1 _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um