From patchwork Fri Sep 2 15:14:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Abel Vesa X-Patchwork-Id: 602221 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 528C2ECAAD5 for ; Fri, 2 Sep 2022 15:32:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236908AbiIBPco (ORCPT ); Fri, 2 Sep 2022 11:32:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49334 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236548AbiIBPcY (ORCPT ); Fri, 2 Sep 2022 11:32:24 -0400 Received: from mail-wr1-x42b.google.com (mail-wr1-x42b.google.com [IPv6:2a00:1450:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D4F729828 for ; Fri, 2 Sep 2022 08:15:00 -0700 (PDT) Received: by mail-wr1-x42b.google.com with SMTP id b5so2722691wrr.5 for ; Fri, 02 Sep 2022 08:15:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date; bh=7Woa6saHlcsqIiHSXMMSyYnI6pEpe3JjUt9ToPHjSVc=; b=zvTQisGu7Utjpmg7NStfiBPYJGrLEtYn4b2DMeUfX2NFLX3/z+Mv0dXr5OlYgoqt7L oMzsQ0fhUGYvi0KdkycR04vYJbUzKI/NoZWzzYTVqFFdc3tleFmPiKo2d3ymZCgzJRbV dmTrgjfAGhddobhhTCJxDpYHydYF6VR1+T0EV9NLaq8YWSDf2oCO2VOrXQCmckTS7/9G H9z7A4sQgtFuWcYPw2w8ExFxSo0OmrC2cHyLCapJJW6cu5nVr7U58PU5WXzeVnUenYUf q/fkWnQBp5ZBf+fj9HLeKuvJwI1SqyJuXhubFkDYvRvR3GIfug8dGkDrY3j8mcghqEuq RLaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date; bh=7Woa6saHlcsqIiHSXMMSyYnI6pEpe3JjUt9ToPHjSVc=; b=WyU5flgclt4mpi4xR87BkhKkuI7uIo4oX2rjxP4TVpG748ZDHZQOAUMuznjeDCQhqO m3CEf5RtEP7uY9Q2w7RbbR4NJLMjdW2Roj77Yupsxh8XEkJU0/L6X3wC+Auc80xvxzJq 3NW7I3BDUapwUw6ZthdP00+wQ4/jPeqt/oKSJ+ZsqmWlZ9IzSjIVW047r/UD79sOhkl7 hItVBHT5XjdypVTnD49/yRAlaEvgxYLfrs2YW+DTaLh2FuwZm7vZLCmnwpUuhY/hczka DvpyMl8ZrUFM0AEwd8SpofPBBq1r73ea4LW6PzKEVhDRV6YIorK206KkeHktv9xIst6L qDXg== X-Gm-Message-State: ACgBeo2/a8Yv+WLFl8ywsm8rSm98OeuNR7C+KbocU0x8Xh2Sr55yP2yI KITKRwP1kueW4TmFwdnkSRSm8Q== X-Google-Smtp-Source: AA6agR47s6LZ7URck0z+aWYLm4j0Hqze93FHpXJcyDcX7Npe9C2JConVK4hs9FfI9+mXKSM6lA+1DQ== X-Received: by 2002:adf:dec9:0:b0:226:e033:c048 with SMTP id i9-20020adfdec9000000b00226e033c048mr12330529wrn.577.1662131699369; Fri, 02 Sep 2022 08:14:59 -0700 (PDT) Received: from hackbox.lan ([94.52.112.99]) by smtp.gmail.com with ESMTPSA id w10-20020a05600c014a00b003a4efb794d7sm2361493wmm.36.2022.09.02.08.14.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 02 Sep 2022 08:14:58 -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 1/3] misc: fastrpc: Fix use-after-free and race in fastrpc_map_find Date: Fri, 2 Sep 2022 18:14:21 +0300 Message-Id: <20220902151423.3351414-1-abel.vesa@linaro.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Currently, there is a race window between the point when the mutex is unlocked in fastrpc_map_lookup and the reference count increasing (fastrpc_map_get) in fastrpc_map_find, which can also lead to use-after-free. So lets merge fastrpc_map_find into fastrpc_map_lookup which allows us to both protect the maps list by also taking the &fl->lock spinlock and the reference count, since the spinlock will be released only after. Add take_ref argument to make this suitable for all callers. Fixes: 8f6c1d8c4f0c ("misc: fastrpc: Add fdlist implementation") Co-developed-by: Ola Jeppsson Signed-off-by: Ola Jeppsson Signed-off-by: Abel Vesa Reviewed-by: Srinivas Kandagatla --- drivers/misc/fastrpc.c | 41 +++++++++++++++++++++-------------------- 1 file changed, 21 insertions(+), 20 deletions(-) diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 93ebd174d848..0c816a11eeec 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -333,30 +333,31 @@ static void fastrpc_map_get(struct fastrpc_map *map) static int fastrpc_map_lookup(struct fastrpc_user *fl, int fd, - struct fastrpc_map **ppmap) + struct fastrpc_map **ppmap, bool take_ref) { + struct fastrpc_session_ctx *sess = fl->sctx; struct fastrpc_map *map = NULL; + int ret = -ENOENT; - mutex_lock(&fl->mutex); + spin_lock(&fl->lock); list_for_each_entry(map, &fl->maps, node) { - if (map->fd == fd) { - *ppmap = map; - mutex_unlock(&fl->mutex); - return 0; - } - } - mutex_unlock(&fl->mutex); - - return -ENOENT; -} + if (map->fd != fd) + continue; -static int fastrpc_map_find(struct fastrpc_user *fl, int fd, - struct fastrpc_map **ppmap) -{ - int ret = fastrpc_map_lookup(fl, fd, ppmap); + if (take_ref) { + ret = fastrpc_map_get(map); + if (ret) { + dev_dbg(sess->dev, "%s: Failed to get map fd=%d ret=%d\n", + __func__, fd, ret); + break; + } + } - if (!ret) - fastrpc_map_get(*ppmap); + *ppmap = map; + ret = 0; + break; + } + spin_unlock(&fl->lock); return ret; } @@ -703,7 +704,7 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd, struct fastrpc_map *map = NULL; int err = 0; - if (!fastrpc_map_find(fl, fd, ppmap)) + if (!fastrpc_map_lookup(fl, fd, ppmap, true)) return 0; map = kzalloc(sizeof(*map), GFP_KERNEL); @@ -1026,7 +1027,7 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx, for (i = 0; i < FASTRPC_MAX_FDLIST; i++) { if (!fdlist[i]) break; - if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap)) + if (!fastrpc_map_lookup(fl, (int)fdlist[i], &mmap, false)) fastrpc_map_put(mmap); }