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Tue, 13 Apr 2021 08:54:33 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D8DCC2C4B2093; Tue, 13 Apr 2021 08:54:33 +0200 (CEST) Date: Tue, 13 Apr 2021 08:54:33 +0200 From: Peter Zijlstra To: Kees Cook Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, x86@kernel.org, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com, chris@chris-wilson.co.uk, intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, hch@lst.de Subject: Re: [PATCH 6/7] i915: Convert to verify_page_range() Message-ID: References: <20210412080012.357146277@infradead.org> <20210412080611.902470568@infradead.org> <202104121306.3A73BEB0A5@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202104121306.3A73BEB0A5@keescook> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 3D0AB600010E X-Stat-Signature: 19c845iho8jgp8f7dyfynpg4tcd6463t Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf09; identity=mailfrom; envelope-from=""; helo=desiato.infradead.org; client-ip=90.155.92.199 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618296882-311498 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, Apr 12, 2021 at 01:08:38PM -0700, Kees Cook wrote: > On Mon, Apr 12, 2021 at 10:00:18AM +0200, Peter Zijlstra wrote: > > @@ -1249,14 +1249,14 @@ static int check_absent_pte(pte_t *pte, > > > > static int check_present(unsigned long addr, unsigned long len) > > { > > - return apply_to_page_range(current->mm, addr, len, > > - check_present_pte, (void *)addr); > > + return verify_page_range(current->mm, addr, len, > > + check_present_pte, (void *)addr); > > For example, switch to returning bad addr through verify_page_range(), > or have a by-reference value, etc: > > unsigned long failed; > > failed = verify_page_range(current->mm< addr, len, check_present_pte); > if (failed) { > pr_err("missing PTE:%lx\n", > (addr - failed) >> PAGE_SHIFT); OK, lemme try that.