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[2003:cb:c709:b200:f007:5a26:32e7:8ef5]) by smtp.gmail.com with ESMTPSA id f6sm12074802wrj.26.2022.01.31.06.28.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 31 Jan 2022 06:28:37 -0800 (PST) Message-ID: Date: Mon, 31 Jan 2022 15:28:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Subject: Re: [PATCH 3/4] mm/usercopy: Detect large folio overruns To: "Matthew Wilcox (Oracle)" , Kees Cook Cc: linux-mm@kvack.org, linux-hardening@vger.kernel.org References: <20220110231530.665970-1-willy@infradead.org> <20220110231530.665970-4-willy@infradead.org> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20220110231530.665970-4-willy@infradead.org> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=FkfeEjoM; spf=none (imf15.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.129.124) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-Rspam-User: nil X-Rspamd-Queue-Id: 8D5E2A0002 X-Stat-Signature: znwiie18g8nzwtcp954qxz4gh3h4pa5e X-Rspamd-Server: rspam12 X-HE-Tag: 1643639321-486370 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 11.01.22 00:15, Matthew Wilcox (Oracle) wrote: > Move the compound page overrun detection out of > CONFIG_HARDENED_USERCOPY_PAGESPAN and convert it to use folios so it's > enabled for more people. > > Signed-off-by: Matthew Wilcox (Oracle) > Acked-by: Kees Cook > --- > mm/usercopy.c | 10 ++++------ > 1 file changed, 4 insertions(+), 6 deletions(-) > > diff --git a/mm/usercopy.c b/mm/usercopy.c > index dcf71b7e3098..e1cb98087a05 100644 > --- a/mm/usercopy.c > +++ b/mm/usercopy.c > @@ -164,7 +164,6 @@ static inline void check_page_span(const void *ptr, unsigned long n, > { > #ifdef CONFIG_HARDENED_USERCOPY_PAGESPAN > const void *end = ptr + n - 1; > - struct page *endpage; > bool is_reserved, is_cma; > > /* > @@ -195,11 +194,6 @@ static inline void check_page_span(const void *ptr, unsigned long n, > ((unsigned long)end & (unsigned long)PAGE_MASK))) > return; > > - /* Allow if fully inside the same compound (__GFP_COMP) page. */ > - endpage = virt_to_head_page(end); > - if (likely(endpage == page)) > - return; > - > /* > * Reject if range is entirely either Reserved (i.e. special or > * device memory), or CMA. Otherwise, reject since the object spans > @@ -259,6 +253,10 @@ static inline void check_heap_object(const void *ptr, unsigned long n, > if (folio_test_slab(folio)) { > /* Check slab allocator for flags and size. */ > __check_heap_object(ptr, n, folio_slab(folio), to_user); > + } else if (folio_test_large(folio)) { > + unsigned long offset = ptr - folio_address(folio); Nit: I'd have added an empty line. > + if (offset + n > folio_size(folio)) > + usercopy_abort("page alloc", NULL, to_user, offset, n); > } else { > /* Verify object does not incorrectly span multiple pages. */ > check_page_span(ptr, n, folio_page(folio, 0), to_user); LGTM Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb