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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id t23sm244439pju.15.2021.04.12.13.05.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 12 Apr 2021 13:05:10 -0700 (PDT) Date: Mon, 12 Apr 2021 13:05:09 -0700 From: Kees Cook To: Peter Zijlstra 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 4/7] mm: Introduce verify_page_range() Message-ID: <202104121302.57D7EF8@keescook> References: <20210412080012.357146277@infradead.org> <20210412080611.769864829@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210412080611.769864829@infradead.org> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 118C9E00011E X-Stat-Signature: rhzqm3fp8trfixjbtbqbbazs8e88knan Received-SPF: none (chromium.org>: No applicable sender policy available) receiver=imf21; identity=mailfrom; envelope-from=""; helo=mail-pf1-f180.google.com; client-ip=209.85.210.180 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618257910-884477 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 10:00:16AM +0200, Peter Zijlstra wrote: > +struct vpr_data { > + int (*fn)(pte_t pte, unsigned long addr, void *data); > + void *data; > +}; Eeerg. This is likely to become an attack target itself. Stored function pointer with stored (3rd) argument. This doesn't seem needed: only DRM uses it, and that's for error reporting. I'd rather plumb back errors in a way to not have to add another place in the kernel where we do func+arg stored calling. -- Kees Cook