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[198.84.205.232]) by smtp.googlemail.com with ESMTPSA id f24-v6sm4239875ioc.52.2018.08.26.10.30.55 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 26 Aug 2018 10:31:00 -0700 (PDT) Subject: Re: [PATCH] net: sched: Fix memory exposure from short TCA_U32_SEL To: Kees Cook , Al Viro Cc: LKML , Cong Wang , Jiri Pirko , "David S. Miller" , Network Development References: <20180826055801.GA42063@beast> <20180826061534.GT6515@ZenIV.linux.org.uk> From: Jamal Hadi Salim Message-ID: <5c88b08d-b9ca-f3df-ae78-cf685ee6723a@mojatatu.com> Date: Sun, 26 Aug 2018 13:30:34 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018-08-26 2:19 a.m., Kees Cook wrote: > On Sat, Aug 25, 2018 at 11:15 PM, Al Viro wrote: >> On Sat, Aug 25, 2018 at 10:58:01PM -0700, Kees Cook wrote: >> Saner approach would be sel_size = offsetof(struct tc_u32_sel, keys[s->nkeys])... > > Either is fine by me. > >>> + sel_size = struct_size(s, keys, s->nkeys); >>> + if (nla_len(tb[TCA_U32_SEL]) < sel_size) { >>> + err = -EINVAL; >>> + goto erridr; >>> + } >>> >>> - n = kzalloc(sizeof(*n) + s->nkeys*sizeof(struct tc_u32_key), GFP_KERNEL); >>> + n = kzalloc(offsetof(typeof(*n), sel) + sel_size, GFP_KERNEL); >> >> ITYM >> n = kzalloc(offsetof(struct tc_u_common, sel.keys[s->nkeys]), GFP_KERNEL); > > I prefer to reuse sel_size and keep typeof() to keep things tied to > "n" more directly. *shrug* Looks good to me. We should add an nla_policy later. Acked-by: Jamal Hadi Salim cheers, jamal