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 X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8BA7C10F11 for ; Wed, 24 Apr 2019 14:56:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A374121903 for ; Wed, 24 Apr 2019 14:56:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556117814; bh=+U7kIkfNl3p5D5Qc1w5yryv07uz6UAhQPCv6Mz6CDqg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=IyCJmHMtW3txrOKFWHW6vqdYcLUz71/rRxpZrPhLAx1oijU1+AEfTMWJxBVadxRnD I3liNNND9Wrf0v7ziC8T4OF3BmyG0edsLO7mC8MdOgrfsdtIWOCcLgUFDHGGQpCP3M 2D1Zpp7T3uBRdVR3v7cEZVIzezPCh1S3I+dVTVbo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732952AbfDXO4x (ORCPT ); Wed, 24 Apr 2019 10:56:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:49714 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732566AbfDXOu2 (ORCPT ); Wed, 24 Apr 2019 10:50:28 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C681D218FC; Wed, 24 Apr 2019 14:50:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556117427; bh=+U7kIkfNl3p5D5Qc1w5yryv07uz6UAhQPCv6Mz6CDqg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GtLJpyq5dbMU/h4jo6i89HvmZLJ5wTI0AxOrB3xRY3A0cdGyye3R3oTDWopR0dRk6 63PC8UtXDQ90JOmojTcUX2B0KhPOjbJR0ra7Ycgb2fw/5OMh+O6wUB32+rqvurKl6y kvwMlTyIuCWdAvfcB46yC/IAkq35edQTkgPSMT6M= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sven Eckelmann , Simon Wunderlich , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.9 06/28] batman-adv: Reduce tt_global hash refcnt only for removed entry Date: Wed, 24 Apr 2019 10:49:50 -0400 Message-Id: <20190424145012.30886-6-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190424145012.30886-1-sashal@kernel.org> References: <20190424145012.30886-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sven Eckelmann [ Upstream commit f131a56880d10932931e74773fb8702894a94a75 ] The batadv_hash_remove is a function which searches the hashtable for an entry using a needle, a hashtable bucket selection function and a compare function. It will lock the bucket list and delete an entry when the compare function matches it with the needle. It returns the pointer to the hlist_node which matches or NULL when no entry matches the needle. The batadv_tt_global_free is not itself protected in anyway to avoid that any other function is modifying the hashtable between the search for the entry and the call to batadv_hash_remove. It can therefore happen that the entry either doesn't exist anymore or an entry was deleted which is not the same object as the needle. In such an situation, the reference counter (for the reference stored in the hashtable) must not be reduced for the needle. Instead the reference counter of the actually removed entry has to be reduced. Otherwise the reference counter will underflow and the object might be freed before all its references were dropped. The kref helpers reported this problem as: refcount_t: underflow; use-after-free. Fixes: 7683fdc1e886 ("batman-adv: protect the local and the global trans-tables with rcu") Reported-by: Martin Weinelt Signed-off-by: Sven Eckelmann Acked-by: Antonio Quartulli Signed-off-by: Simon Wunderlich Signed-off-by: Sasha Levin --- net/batman-adv/translation-table.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c index 4f18fcd2d3c0..af4a02ad8503 100644 --- a/net/batman-adv/translation-table.c +++ b/net/batman-adv/translation-table.c @@ -615,14 +615,26 @@ static void batadv_tt_global_free(struct batadv_priv *bat_priv, struct batadv_tt_global_entry *tt_global, const char *message) { + struct batadv_tt_global_entry *tt_removed_entry; + struct hlist_node *tt_removed_node; + batadv_dbg(BATADV_DBG_TT, bat_priv, "Deleting global tt entry %pM (vid: %d): %s\n", tt_global->common.addr, BATADV_PRINT_VID(tt_global->common.vid), message); - batadv_hash_remove(bat_priv->tt.global_hash, batadv_compare_tt, - batadv_choose_tt, &tt_global->common); - batadv_tt_global_entry_put(tt_global); + tt_removed_node = batadv_hash_remove(bat_priv->tt.global_hash, + batadv_compare_tt, + batadv_choose_tt, + &tt_global->common); + if (!tt_removed_node) + return; + + /* drop reference of remove hash entry */ + tt_removed_entry = hlist_entry(tt_removed_node, + struct batadv_tt_global_entry, + common.hash_entry); + batadv_tt_global_entry_put(tt_removed_entry); } /** -- 2.19.1