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([2001:a61:24b3:de01:7310:e730:497d:ea6a]) by smtp.gmail.com with ESMTPSA id l23sm11535934wmh.40.2020.11.27.01.30.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 Nov 2020 01:30:45 -0800 (PST) Cc: mtk.manpages@gmail.com, tglx@linutronix.de, mingo@kernel.org, luto@kernel.org, x86@kernel.org, len.brown@intel.com, dave.hansen@intel.com, hjl.tools@gmail.com, Dave.Martin@arm.com, mpe@ellerman.id.au, tony.luck@intel.com, ravi.v.shankar@intel.com, libc-alpha@sourceware.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, Fenghua Yu Subject: Re: [PATCH v2 2/4] x86/elf: Support a new ELF aux vector AT_MINSIGSTKSZ To: Borislav Petkov , "Chang S. Bae" , Dave Martin References: <20201119190237.626-1-chang.seok.bae@intel.com> <20201119190237.626-3-chang.seok.bae@intel.com> <20201126174418.GA29770@zn.tnic> From: "Michael Kerrisk (man-pages)" Message-ID: <7b2b1f7f-75e5-01ab-7571-71340825d299@gmail.com> Date: Fri, 27 Nov 2020 10:30:44 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201126174418.GA29770@zn.tnic> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hey Dave Marin, On 11/26/20 6:44 PM, Borislav Petkov wrote: > On Thu, Nov 19, 2020 at 11:02:35AM -0800, Chang S. Bae wrote: >> Historically, signal.h defines MINSIGSTKSZ (2KB) and SIGSTKSZ (8KB), for >> use by all architectures with sigaltstack(2). Over time, the hardware state >> size grew, but these constants did not evolve. Today, literal use of these >> constants on several architectures may result in signal stack overflow, and >> thus user data corruption. >> >> A few years ago, the ARM team addressed this issue by establishing >> getauxval(AT_MINSIGSTKSZ), such that the kernel can supply at runtime value >> that is an appropriate replacement on the current and future hardware. >> >> Add getauxval(AT_MINSIGSTKSZ) support to x86, analogous to the support >> added for ARM in commit 94b07c1f8c39 ("arm64: signal: Report signal frame >> size to userspace via auxv"). > > I don't see it documented here: > > https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/man3/getauxval.3 > > Dunno, now that two architectures will have it, maybe that is good > enough reason to document it. > > Adding Michael. Commit 94b07c1f8c39 was your, Dave. Might I convince you to write a patch for getauxval(3)? Thanks, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/