From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80D73C001B5 for ; Fri, 2 Sep 2022 15:33:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236714AbiIBPc5 (ORCPT ); Fri, 2 Sep 2022 11:32:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236606AbiIBPcZ (ORCPT ); Fri, 2 Sep 2022 11:32:25 -0400 Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4F9F656E for ; Fri, 2 Sep 2022 08:15:03 -0700 (PDT) Received: by mail-wm1-x331.google.com with SMTP id m17-20020a7bce11000000b003a5bedec07bso3539566wmc.0 for ; Fri, 02 Sep 2022 08:15:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date; bh=ppnIzcD1Lvog5KH9Fyfxjv2BYJnZPxI6mOxm9069x0Q=; b=Fvsdo4X7t20LzXiT5gHh6YEPAklYxulIy6hd9e1+71rOqYERWz3mUY8QIpce1YWs5c T4GxcW+az/HLD9HYS7mo1WII36FmPQ62/cGEAJtSHd4mhVyFpkXKXjTmAPX2rHvb9Yjl Wqc40omyd0iKDDLJkDYsYX1UUrW1NYCPYzx04NkdrKpDmvNTUK+atIJDatnxUJVTIaz3 R8GCtkFGKGeMd5D+tqYAvs2oChSOTCBt9HUJDvR+iJzpcZFrBlyA72C7ZuMddbEhzxMw A8TXhu5Zpw2yscF2sKZ8r07wchn6YlROakTcdPXQ15+/Q4SU9f2bcjlVF3nZWT5YWHjq 3lyA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=ppnIzcD1Lvog5KH9Fyfxjv2BYJnZPxI6mOxm9069x0Q=; b=NNP6ihMXlhC0Ys4SFUia+KwLEpt/puoDwoV4oPb0flCGRl8OHixIWXBDG76mwVOMjC Do9DreXh523dEJ+LOtss7Gp66+6jia5QtZrp+X7yZluxd35Uz2ibMYTJ/1iz01VBjOdZ OlKx25wJcvDOp9CxKjIDKVqhRqlldlV2hIfr9qZ/gt+XhBbIrRTivpe728BsJOvrFZBM RJM4jMcj+SpBMe9HXo77jECIxPhUovaBfDdXHXCABtLabKgvVnYWJrT2ba6HtJ/h7oOq L7O0IGFHPo1cGC3paHAX9is99mC0Fx9J3TsgbcEjPBrbsxuxyqVoJwAt+TeKWLY4MHPW 5+lw== X-Gm-Message-State: ACgBeo2WiZE9AUq9c0vcAAJeD0nqdkn1hLxxnAWF4pB3yez7v1Ay6aoK 0xtW6rDwuPm3HMIUQVne1Z1wQA== X-Google-Smtp-Source: AA6agR7FlLcf18Fay4hYuE/8S7Rn5LcJExIwtFG5sZbJLUHX9IIteBZnXfpei+us/9OKzgyeQZXOyg== X-Received: by 2002:a05:600c:2311:b0:3a6:84e5:bcad with SMTP id 17-20020a05600c231100b003a684e5bcadmr3239020wmo.72.1662131702350; Fri, 02 Sep 2022 08:15:02 -0700 (PDT) Received: from hackbox.lan ([94.52.112.99]) by smtp.gmail.com with ESMTPSA id w10-20020a05600c014a00b003a4efb794d7sm2361493wmm.36.2022.09.02.08.15.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Sep 2022 08:15:01 -0700 (PDT) From: Abel Vesa To: Srinivas Kandagatla , Amol Maheshwari , Ekansh Gupta , Vamsi Krishna Gattupalli Cc: Arnd Bergmann , Greg Kroah-Hartman , linux-arm-msm@vger.kernel.org, Linux Kernel Mailing List , Ola Jeppsson Subject: [PATCH 3/3] misc: fastrpc: Fix use-after-free race condition for maps Date: Fri, 2 Sep 2022 18:14:23 +0300 Message-Id: <20220902151423.3351414-3-abel.vesa@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220902151423.3351414-1-abel.vesa@linaro.org> References: <20220902151423.3351414-1-abel.vesa@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ola Jeppsson It is possible that in between calling fastrpc_map_get() until map->fl->lock is taken in fastrpc_free_map(), another thread can call fastrpc_map_lookup() and get a reference to a map that is about to be deleted. Rewrite fastrpc_map_get() to only increase the reference count of a map if it's non-zero. Propagate this to callers so they can know if a map is about to be deleted. Fixes this warning: refcount_t: addition on 0; use-after-free. WARNING: CPU: 5 PID: 10100 at lib/refcount.c:25 refcount_warn_saturate ... Call trace: refcount_warn_saturate [fastrpc_map_get inlined] [fastrpc_map_lookup inlined] fastrpc_map_create fastrpc_internal_invoke fastrpc_device_ioctl __arm64_sys_ioctl invoke_syscall Fixes: c68cfb718c8f9 ("misc: fastrpc: Add support for context Invoke method") Signed-off-by: Ola Jeppsson Signed-off-by: Abel Vesa --- drivers/misc/fastrpc.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 50c17f5da3a8..58654d394d17 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -332,10 +332,12 @@ static void fastrpc_map_put(struct fastrpc_map *map) kref_put(&map->refcount, fastrpc_free_map); } -static void fastrpc_map_get(struct fastrpc_map *map) +static int fastrpc_map_get(struct fastrpc_map *map) { - if (map) - kref_get(&map->refcount); + if (!map) + return -ENOENT; + + return kref_get_unless_zero(&map->refcount) ? 0 : -ENOENT; } -- 2.34.1