From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 365B641D11C; Fri, 4 Sep 2026 06:07:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788502075; cv=none; b=CZnGIbDnBu6h0NFT+OERw/SkmOpxycWP+dRps7CHm82YhPtd8O7H5wcBH23rBN3MwfDDneZEEWxmMwjZ2RJu3zGFkO3rdykXkFpO8bMoBe85fSGKzsDSV937QgIH1255yb5C1SW9fAQcLiz4gjl04JPjuY1gx0vL4rxUIm9HbFA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788502075; c=relaxed/simple; bh=rxaUHLGU9k6tPzoj4hOXz72TDIsa3Zb4x9vgr5/hMYw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bzmFRfqQHYIHrRR5elMgk7HRUyYXtUorRYdQ5uAq/aXWgRVP8CY0QSbEli/lf8qvCjXzos8Z6lFNRAEgK2JeGIs68kt4XuTvfbDQEqlFGb25jqwa4udQ618YJbLZPYoH8Yva7EMzw/8L26Z8jkow9W0FuOFdSxQ3EW4w0hN2kAg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=XjXn5ApS; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="XjXn5ApS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 852351F00A3E; Fri, 4 Sep 2026 06:07:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788502073; bh=MgTnFyfhwjLTAvVYlsXi38gxSyU5qNipRCwfimNyOa8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=XjXn5ApS3VQn/NPK47A8eHPAB78mB8wZA6+sONgWLTHN1wbmNSvqWQJXkpkGvVsZN L6Rw/Qn3rc2hnkrZQyq8sUus4Js657vgkZofv+5CHNFmT8mXgdZXn9kLTpF3ISnCPk +o70HZMVn69g70NS52PxXcJhNW0g8gd54b0jeMBY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, James Kim , Dan Carpenter , Alexandre Bounine , Matt Porter , Andrew Morton Subject: [PATCH 6.12 043/403] rapidio: mport_cdev: fix use-after-free in dma_req_free() Date: Fri, 4 Sep 2026 06:57:26 +0200 Message-ID: <20260904045735.794636555@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260904045734.806166532@linuxfoundation.org> References: <20260904045734.806166532@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: James Kim commit 5cbef379a94b161726c5f504598bf4791d45cedc upstream. dma_req_free() acquires buf_mutex through req->map, drops the mapping reference with kref_put(), and then dereferences req->map again to unlock the mutex. If kref_put() drops the last reference, mport_release_mapping() frees the mapping, and the subsequent mutex_unlock() dereferences a freed object. This is a use-after-free. Fix this by caching map and md before kref_put(), clearing req->map while holding buf_mutex, and using the cached md for mutex unlocking. The bug is reachable from userspace via the RapidIO mport character device interface. Link: https://lore.kernel.org/20260723235220.588424-1-james010kim@gmail.com Fixes: e8de370188d0 ("rapidio: add mport char device driver") Signed-off-by: James Kim Reviewed-by: Dan Carpenter Cc: Alexandre Bounine Cc: Greg Kroah-Hartman Cc: Matt Porter Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- drivers/rapidio/devices/rio_mport_cdev.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/drivers/rapidio/devices/rio_mport_cdev.c +++ b/drivers/rapidio/devices/rio_mport_cdev.c @@ -584,9 +584,13 @@ static void dma_req_free(struct kref *re } if (req->map) { - mutex_lock(&req->map->md->buf_mutex); - kref_put(&req->map->ref, mport_release_mapping); - mutex_unlock(&req->map->md->buf_mutex); + struct rio_mport_mapping *map = req->map; + struct mport_dev *md = map->md; + + mutex_lock(&md->buf_mutex); + req->map = NULL; + kref_put(&map->ref, mport_release_mapping); + mutex_unlock(&md->buf_mutex); } kref_put(&priv->dma_ref, mport_release_dma);