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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id u4-20020a170902a60400b0015eab1b097dsm125753plq.22.2022.05.10.14.54.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 May 2022 14:54:48 -0700 (PDT) Date: Tue, 10 May 2022 14:54:47 -0700 From: Kees Cook To: Andrew Morton Cc: Yuanzheng Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Matthew Wilcox Subject: Re: [PATCH] mm: usercopy: move the virt_addr_valid() below the is_vmalloc_addr() Message-ID: <202205101453.145A1C4F@keescook> References: <20220505071037.4121100-1-songyuanzheng@huawei.com> <20220509203732.951da2e00ddfa628decf24a2@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220509203732.951da2e00ddfa628decf24a2@linux-foundation.org> X-Stat-Signature: rytu5xmufaztmq5buxyq8dduksn6mk75 X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 5073D160089 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=lSjEVHno; spf=pass (imf08.hostedemail.com: domain of keescook@chromium.org designates 209.85.214.171 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Rspam-User: X-HE-Tag: 1652219676-524005 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 09, 2022 at 08:37:32PM -0700, Andrew Morton wrote: > Matthew & Kees, > > On Thu, 5 May 2022 07:10:37 +0000 Yuanzheng Song wrote: > > > The is_kmap_addr() and the is_vmalloc_addr() in the check_heap_object() > > will not work, because the virt_addr_valid() will exclude the kmap and > > vmalloc regions. So let's move the virt_addr_valid() below > > the is_vmalloc_addr(). > > The author, > > > Signed-off-by: Yuanzheng Song > > Tells me off-list that this fix: > > > --- a/mm/usercopy.c > > +++ b/mm/usercopy.c > > @@ -163,9 +163,6 @@ static inline void check_heap_object(const void *ptr, unsigned long n, > > { > > struct folio *folio; > > > > - if (!virt_addr_valid(ptr)) > > - return; > > - > > if (is_kmap_addr(ptr)) { > > unsigned long page_end = (unsigned long)ptr | (PAGE_SIZE - 1); > > > > @@ -190,6 +187,9 @@ static inline void check_heap_object(const void *ptr, unsigned long n, > > return; > > } > > > > + if (!virt_addr_valid(ptr)) > > + return; > > + > > folio = virt_to_folio(ptr); > > > > if (folio_test_slab(folio)) { > > is required to fix patches "mm/usercopy: Check kmap addresses properly" > and "mm/usercopy: Detect vmalloc overruns". Ah, this very well may be true! I will need to study this (or more likely, I will build some selftests), but I suspect willy knows off the top of his head. :) -- Kees Cook