From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZprQyqGPb459WcKqyZHhM89tdz6Rnj4hAbAXOyzRJniKknylQGpaa/521mm3zMhx5YHVgcS ARC-Seal: i=1; a=rsa-sha256; t=1526937500; cv=none; d=google.com; s=arc-20160816; b=l6kF2M5iaUvXz4wxf8nF+DEqEnsxI3cLPW/e9+PSbCU46d1tvnXJp78BTdQazCFnFy Lxby9+yOpN+d6TOzbuoc4EKEEDfL3WaqEx0YGTRKEP7hAM2CAiWtBDSmFoJVEQxy/bPi PGZ2M/g+cMVKovEiFd340ZeFlPxU508VTPLfHH5bSToUzFuUqVPe1VJlIHkGKPrsoddI M4/dq/EnXMSj9RCPcye14k7QKRgk8cgUmvwEKyUR5GMTHn9hvDefbHoyOGyV1FTj/Vra rkEX4CTnv5qjgj3oS37ygPj6k1GrPKbrG8g6pG/3fIeGqFzVnWazSQA4UqJ1ZQ8sinf4 Azqw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=wjNcoXoYTYFgt0K6+q3cFP/Uflgw6HjpgHHlicWxvp4=; b=TRzJkEvgkvfsnS36XvYiYvjQUE2aCXUh2HPP/riY8WsIETZxpRe69X8ep6vAT0/1Wv rLa7/oVEDC3pvGa9Ch6E3+zYPzBet/AKfxnGoQz714MTSCqF7TuRBkX3JBZ4kleC7bdG HS3f8cQJrrX2QpWw6NW8ZMu2ejfNL8ZDIEIklg2q0xYcC3hroTJ33Ef9WuZWwOxFSq19 60C2oJCQd40PUjhEw9l3TK6BSKELI6oevTPjOO50sKxRQnpuGfW3HXwOimA4yao4kDLm wdZEkMcBnwbeFDbfIm2eaIGw3g+qw4BBdpihDCmx339kglkftvLEZUY1Daa6xuvnzyQQ 1RBw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=o/PLEDzx; spf=pass (google.com: domain of srs0=nia/=ii=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=nia/=II=linuxfoundation.org=gregkh@kernel.org Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=o/PLEDzx; spf=pass (google.com: domain of srs0=nia/=ii=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=nia/=II=linuxfoundation.org=gregkh@kernel.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , Jens Wiklander Subject: [PATCH 4.14 17/95] tee: shm: fix use-after-free via temporarily dropped reference Date: Mon, 21 May 2018 23:11:07 +0200 Message-Id: <20180521210451.210684927@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180521210447.219380974@linuxfoundation.org> References: <20180521210447.219380974@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1601110016429100028?= X-GMAIL-MSGID: =?utf-8?q?1601110016429100028?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit bb765d1c331f62b59049d35607ed2e365802bef9 upstream. Bump the file's refcount before moving the reference into the fd table, not afterwards. The old code could drop the file's refcount to zero for a short moment before calling get_file() via get_dma_buf(). This code can only be triggered on ARM systems that use Linaro's OP-TEE. Fixes: 967c9cca2cc5 ("tee: generic TEE subsystem") Signed-off-by: Jann Horn Signed-off-by: Jens Wiklander Signed-off-by: Greg Kroah-Hartman --- drivers/tee/tee_shm.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/drivers/tee/tee_shm.c +++ b/drivers/tee/tee_shm.c @@ -203,9 +203,10 @@ int tee_shm_get_fd(struct tee_shm *shm) if ((shm->flags & req_flags) != req_flags) return -EINVAL; + get_dma_buf(shm->dmabuf); fd = dma_buf_fd(shm->dmabuf, O_CLOEXEC); - if (fd >= 0) - get_dma_buf(shm->dmabuf); + if (fd < 0) + dma_buf_put(shm->dmabuf); return fd; }