From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 79BAB2590 for ; Sun, 22 Jan 2023 15:24:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED287C433D2; Sun, 22 Jan 2023 15:24:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1674401065; bh=Cs0kR9ym3aFap91K8EOWnZ+TEw7El+zLbkemAYeRP8k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zm6WQEVU7nVTbweMqKYAW2zGQTphqU1lLExTHBbt9ePEZ7jlao/ErJk4LbvZ2x9kf LnH5vgYggY5dJv7PsJIbSA541vCsOainW/5Nbno0LAxbZ9reWBjWtWt8dtlhAXpypF +CLG5e7D7Pnb6CNeK3cADfJxHmbbueuUB0NHsIsI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Ola Jeppsson , Abel Vesa , Srinivas Kandagatla Subject: [PATCH 6.1 068/193] misc: fastrpc: Fix use-after-free and race in fastrpc_map_find Date: Sun, 22 Jan 2023 16:03:17 +0100 Message-Id: <20230122150249.455763757@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230122150246.321043584@linuxfoundation.org> References: <20230122150246.321043584@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Abel Vesa commit 9446fa1683a7e3937d9970248ced427c1983a1c5 upstream. 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") Cc: stable Co-developed-by: Ola Jeppsson Signed-off-by: Ola Jeppsson Signed-off-by: Abel Vesa Signed-off-by: Srinivas Kandagatla Link: https://lore.kernel.org/r/20221124174941.418450-2-srinivas.kandagatla@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/misc/fastrpc.c | 41 +++++++++++++++++++++-------------------- 1 file changed, 21 insertions(+), 20 deletions(-) --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -333,30 +333,31 @@ static void fastrpc_map_get(struct fastr 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 fas 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 fastr 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); }