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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id b78-20020a621b51000000b0056b4c5dde61sm1898977pfb.98.2022.10.25.15.25.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Oct 2022 15:25:18 -0700 (PDT) From: Kees Cook To: Al Viro , ebiederm@xmission.com, eb@emlix.com Cc: Kees Cook , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH] fs/exec.c: simplify initial stack size expansion Date: Tue, 25 Oct 2022 15:24:39 -0700 Message-Id: <166673667324.2128117.14471012472344174206.b4-ty@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <2017429.gqNitNVd0C@mobilepool36.emlix.com> References: <2017429.gqNitNVd0C@mobilepool36.emlix.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666736720; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=fVyOXaIPwUu5vIxKTkFwgvGCOhZvoDwYK5zKXQji1rw=; b=erWOK4dNz2V/Hh6DxKS0qfAL0InB8Q4S6vAFraZ0zoOyLkGdrgBAOAhw/adXslHeRgyMbc +8TUP1yd7J4+h6zpzOUcycI2XoPHpcOj0RrYgdHMg0DYoyKHUQvcHzslZHj/ABBDmVox5B ahXAM+bSFd7qbGq0UGz2GdcGGUqw3Xo= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=FXN94XTH; spf=pass (imf11.hostedemail.com: domain of keescook@chromium.org designates 209.85.214.182 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666736720; a=rsa-sha256; cv=none; b=vXMZcjf/98LZ9Py+9gkpz+XyXWllfjUfmJRPMVmpMYF5UZYQsc1UgssG3AlewLhh5SG2li mCsk8mSA5Ead5QQIfe1dx3g/9tR66iRtzd0Qqiw9HFCiqddpr6hRQfAzO/WH3VtyLTFPOS haL87MpNHbMJhnG2i7rv5KbHykfxROQ= Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=chromium.org header.s=google header.b=FXN94XTH; spf=pass (imf11.hostedemail.com: domain of keescook@chromium.org designates 209.85.214.182 as permitted sender) smtp.mailfrom=keescook@chromium.org; dmarc=pass (policy=none) header.from=chromium.org X-Stat-Signature: 6e3xdmjqsdoaiomefji9ao7zx3knjj4a X-Rspamd-Queue-Id: 6B3CF40004 X-Rspamd-Server: rspam07 X-Rspam-User: X-HE-Tag: 1666736720-981020 X-Bogosity: Ham, tests=bogofilter, spamicity=0.003425, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 19 Oct 2022 09:32:35 +0200, Rolf Eike Beer wrote: > I had a hard time trying to understand completely why it is using vm_end in > one side of the expression and vm_start in the other one, and using > something in the "if" clause that is not an exact copy of what is used > below. The whole point is that the stack_size variable that was used in the > "if" clause is the difference between vm_start and vm_end, which is not far > away but makes this thing harder to read than it must be. > > [...] Applied to for-next/execve, thanks! [1/1] fs/exec.c: simplify initial stack size expansion https://git.kernel.org/kees/c/bfb4a2b95875 -- Kees Cook