From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [PATCH 4.9 05/78] net: sched: Fix memory exposure from short TCA_U32_SEL Date: Thu, 13 Sep 2018 15:30:52 +0200 Message-ID: <20180913131806.077980471@linuxfoundation.org> References: <20180913131805.732342940@linuxfoundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Al Viro , Jamal Hadi Salim , Cong Wang , Jiri Pirko , "David S. Miller" , netdev@vger.kernel.org, Kees Cook To: linux-kernel@vger.kernel.org Return-path: In-Reply-To: <20180913131805.732342940@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kees Cook [ Upstream commit 98c8f125fd8a6240ea343c1aa50a1be9047791b8 ] Via u32_change(), TCA_U32_SEL has an unspecified type in the netlink policy, so max length isn't enforced, only minimum. This means nkeys (from userspace) was being trusted without checking the actual size of nla_len(), which could lead to a memory over-read, and ultimately an exposure via a call to u32_dump(). Reachability is CAP_NET_ADMIN within a namespace. Reported-by: Al Viro Cc: Jamal Hadi Salim Cc: Cong Wang Cc: Jiri Pirko Cc: "David S. Miller" Cc: netdev@vger.kernel.org Signed-off-by: Kees Cook Acked-by: Jamal Hadi Salim Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/cls_u32.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -851,6 +851,7 @@ static int u32_change(struct net *net, s struct nlattr *opt = tca[TCA_OPTIONS]; struct nlattr *tb[TCA_U32_MAX + 1]; u32 htid, flags = 0; + size_t sel_size; int err; #ifdef CONFIG_CLS_U32_PERF size_t size; @@ -967,8 +968,11 @@ static int u32_change(struct net *net, s return -EINVAL; s = nla_data(tb[TCA_U32_SEL]); + sel_size = sizeof(*s) + sizeof(*s->keys) * s->nkeys; + if (nla_len(tb[TCA_U32_SEL]) < sel_size) + return -EINVAL; - n = kzalloc(sizeof(*n) + s->nkeys*sizeof(struct tc_u32_key), GFP_KERNEL); + n = kzalloc(offsetof(typeof(*n), sel) + sel_size, GFP_KERNEL); if (n == NULL) return -ENOBUFS; @@ -981,7 +985,7 @@ static int u32_change(struct net *net, s } #endif - memcpy(&n->sel, s, sizeof(*s) + s->nkeys*sizeof(struct tc_u32_key)); + memcpy(&n->sel, s, sel_size); RCU_INIT_POINTER(n->ht_up, ht); n->handle = handle; n->fshift = s->hmask ? ffs(ntohl(s->hmask)) - 1 : 0;