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Received: from authenticated user by stravinsky.debian.org with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.94.2) (envelope-from ) id 1sS07b-00An95-JB for linux-mm@kvack.org; Thu, 11 Jul 2024 20:10:31 +0000 Message-ID: <2d7bd8b2b9736d4a7d0a26169978372b5e002a62.camel@debian.org> Subject: Re: [PATCH] mm: huge_memory: don't force huge page alignment on 32 bit From: Yves-Alexis Perez To: Yang Shi , jirislaby@kernel.org, surenb@google.com, riel@surriel.com, willy@infradead.org, cl@linux.com, akpm@linux-foundation.org Cc: yang@os.amperecomputing.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Salvatore Bonaccorso , Ben Hutchings Date: Thu, 11 Jul 2024 22:10:12 +0200 In-Reply-To: <20240118133504.2910955-1-shy828301@gmail.com> References: <20240118133504.2910955-1-shy828301@gmail.com> Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.52.3-1 MIME-Version: 1.0 X-Debian-User: corsac X-Stat-Signature: b9ta54f1twg1sf1w8dbhoh5noob5c3rk X-Rspamd-Queue-Id: 1EFBF18000F X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1720728633-312387 X-HE-Meta: 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 m0rWkaEY kmPLT8x5z9u+vAZiLy3tL1I9hQUyn4OjK9hzlwJwZ2psHAFc2oZwYDuPna2K5JWGwJ7ED0t3C3lDPx8/J0YTdzh68wIfqQ7rZIs1NU0ZYjkH3Qm5fberM77eYAr7nH4tBKxDYVLSOqscaYq58mo+HTN17MSCylEX/pytVsXyVqC6YwG0oBsDNB1OUB1XpOUzx6729prmXFH0p1zh+4ngr0KER22EEiP2kgYUHDAdKXP2ZK2nP+JQI8ymHnnMpiGkdvOCkgfq6hvmkROs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000011, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 On Thu, 2024-01-18 at 05:35 -0800, Yang Shi wrote: > The commit efa7df3e3bb5 ("mm: align larger anonymous mappings on THP > boundaries") caused two issues [1] [2] reported on 32 bit system or compa= t > userspace. >=20 > It doesn't make too much sense to force huge page alignment on 32 bit > system due to the constrained virtual address space. Hi people, sorry for beeing so late. I've looked at this following the OpenSSH issue (CVE-2024-6387 [1]) and especially the impact on IA-32 installations where ASLR is apparently broken. There was a recent thread [2] on oss-security discussing the issue. Looking at the commit log I think the intention was to fix this both for: - - 32 bit process running on 64 bit kernels: in_compat_syscall() - - all processes running on 32 bit kernels: IS_ENABLED(CONFIG_32BIT) Unfortunately, as far as I can tell, CONFIG_32BIT is not enabled on 32bit x= 86 kernels. Maybe CONFIG_X86_32 would be the right one there? [1] https://www.openwall.com/lists/oss-security/2024/07/01/3 [2] https://www.openwall.com/lists/oss-security/2024/07/08/3 - --=20 Yves-Alexis -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEE8vi34Qgfo83x35gF3rYcyPpXRFsFAmaQPCQACgkQ3rYcyPpX RFvSHQf/VE7td7scTTsrK7Cx0F3MmDLFgjUDbMDuyPq6lNQqnDbd2zc00JP1eeLs /mW1uZNbR92bn6xq2sPJu7c6tB3MJuiQme+ZqnPfIgyoWc89i6V6WUXTZN077lIl xJZxHLMei5KreHz66AYU66HdU89knMTcX362YyyI8dEZKXS3FlP0SLSoBM0UKY0G HYM6+GetE+fINhfNSMpHgqkTQB825Vqdq5UBsBjHYMg5RJ92/fDgUo5RD7qm/HVz SDDNSGwpVwYZ20RnnD+DOS9rsnyR4FcAP0m0dcTmQdM8GcY4SyjnEux5idvCicjy a1jmvsSLxCMZ9mZsrsipIZoNhSHlDA=3D=3D =3Df0Lk -----END PGP SIGNATURE-----