From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZqEWVfIXzZb5qIyEV4dOVA9o7A3lc630TQiXZAdTdwRvXMJeppHEreSiqm0y4uJvhNpD9K3 ARC-Seal: i=1; a=rsa-sha256; t=1526937787; cv=none; d=google.com; s=arc-20160816; b=WDAyj2oU/8LAuYmmnJBxg8SJUUCu0/XtbiLqM4+qOnXIubGhYbGzYIATdtRWPp+ooh DFBTNQndgZGvA/BexL/k9MSkg3X5IyWw/KRsVswAOcln8/gbtaGVTGrKn2UrohlRCUoh FbdBRJVmUBXyTyD4O9PwR2WF7GVyIgnuM3CHe1fW/pKR5hsK5Mk47iSJ2bj/GNtDR8rV mC9I14jO8ulDyUPOpvsijIpfOBrISk6FSF+xmklwKIAlOofgDHltPLNJG2NgjmAK+6HT yNG9j74dRqyMcMp6S+45QFwcDHNnkRnQC5FhSjClL74iomD6yNVCAmDBtrZLLVZnVExX dckA== 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=PvLBWf0xdKI2JohKWJZgTukFy14ovpJT7RXSIPzd2Vc=; b=nemNxbS6JoLvdP/HZF5TpbLZJpiJ41Jf1ZvcLolaXR8+UvJhVzRJj0wFVgk9WeaZ5c bSlJo7F7OFRSu81rAo/L8ZbmDcE+iOpQytzzv2LvxxiMWt18hE74qQGy/6fqmvRt8OcE hlE2iiVnZC5yEwxGQPlNlqjY/KstrlWZawLTreEBmTB1Ml3zcTTSSDsZ1G3RLkmrFWdq AEj6fNGOtS5665LNdpeQFcysjkSdDM1VgY8BSFnPMrHwXNdbhw9cGBhLCKv6D7Zfvhwc oOkdUJ1HTcutBGHAIJtt4z9wg4QioIKFs5NlBIQlLFICCM9fW86Xeuscd0TeO4Bh/FGS lC4g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=0+NcutDf; 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=0+NcutDf; 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 4.16 025/110] tee: shm: fix use-after-free via temporarily dropped reference Date: Mon, 21 May 2018 23:11:22 +0200 Message-Id: <20180521210506.066487309@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180521210503.823249477@linuxfoundation.org> References: <20180521210503.823249477@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?1601110317314625125?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.16-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 @@ -360,9 +360,10 @@ int tee_shm_get_fd(struct tee_shm *shm) if (!(shm->flags & TEE_SHM_DMA_BUF)) 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; }