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 BDA771429C for ; Wed, 31 May 2023 14:16:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2F541C433D2; Wed, 31 May 2023 14:16:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1685542585; bh=6xPVFqexSIW7Z9IDBUUq4nFv5EZETSZ0A3H+jexY8Ug=; h=From:To:Cc:Subject:Date:From; b=mO68rUpe21FDD87sqVUTxkHqsjWPBsyqdMq9X0kKabvZb5rCQuye9Ls2ovHj46Esm toJZVU3bPGB+7TO9sKR1unvcK2cqZJgibVtbPqNtD2CxdQtJ7nCuj713Qj0a3hCj5m C4cHGoMroa63d+q6HIrRBBG+XGn2acHkI52BrjqwqN2jU0upMi6Rg4sHrprNQnrgFL +xSP8hbglakFAPuRQ1UmjU7lZLiJWAXqkPSyzGSJ62wQrnArUxbaUvG8LBu9Jsqb4z syWYHiynewVeLFY5S9kOMIrPdz4dNfwP0uMp1x2RV12GwAJntAmp5Iqsrcydl02Y8a 2cj1fk/xnT+Qw== From: Lee Jones To: lee@kernel.org, jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, stable@kernel.org Subject: [PATCH 1/1] net/sched: cls_u32: Fix reference counter leak leading to overflow Date: Wed, 31 May 2023 15:15:56 +0100 Message-ID: <20230531141556.1637341-1-lee@kernel.org> X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit In the event of a failure in tcf_change_indev(), u32_set_parms() will immediately return without decrementing the recently incremented reference counter. If this happens enough times, the counter will rollover and the reference freed, leading to a double free which can be used to do 'bad things'. Cc: stable@kernel.org # v4.14+ Signed-off-by: Lee Jones --- net/sched/cls_u32.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 4e2e269f121f8..fad61ca5e90bf 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -762,8 +762,11 @@ static int u32_set_parms(struct net *net, struct tcf_proto *tp, if (tb[TCA_U32_INDEV]) { int ret; ret = tcf_change_indev(net, tb[TCA_U32_INDEV], extack); - if (ret < 0) + if (ret < 0) { + if (tb[TCA_U32_LINK]) + n->ht_down->refcnt--; return -EINVAL; + } n->ifindex = ret; } return 0; -- 2.41.0.rc0.172.g3f132b7071-goog