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b=yMP49xPvcS99rsgy005XjHRwxlRHA1gCpQC8Ni3WzIqkb+yf/n6tkn+lISYSI3LQe iO9WoTD2rzm/HT2cVC/79WpkQ2l6HjSj+8L1J72bVpfsGIMsLwy4S11SatRJVCItbs aR7txXxrDpNDODeKBftgt8cj7l/+RiZUOmTzT5L0= Date: Tue, 3 Oct 2023 10:17:17 -0700 From: Andrew Morton To: "Arnd Bergmann" Cc: "Gregory Price" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Gregory Price" Subject: Re: [PATCH] mm/migrate: fix do_pages_move for compat pointers Message-Id: <20231003101717.f57af0208431dba6dac0357e@linux-foundation.org> In-Reply-To: References: <20231003144857.752952-1-gregory.price@memverge.com> <20231003094912.08cf57998135446ef475dd19@linux-foundation.org> <325de88f-1237-4910-aa2a-97707bedae26@app.fastmail.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 0E8F72000D X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: bd6fdo3tnswxg5gygeg77abztzcdc6pw X-HE-Tag: 1696353440-602693 X-HE-Meta: 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 lHMR0BCh Z7wdXPfO1eQ71W0qlo7wQR0u05yhTvhYzncOssPlPyyCPqb92ADxRbTJZBVNk+oD9ekOawkPEHYcaNPx8YJmeXI15WeeiMQKDVQvnHjewe5n6qp1cIF+l5azyuEKGiI8nf/cFF7ljPYwT/kc4LD1YfPdMrCKPrLN8vnqYiEJ2jS+f/inRPh/CK2rAF4ESQzPrTNxR9yRshebDbHRMvMcqGDYtv6Y36r4sNMpWeduTbfywFEzTNHQeFG8nlN6mZuH3ZwjJlwrdr0O2qcfhGNwVNE61d/VaJBoBD7rTpr8Fa64wYSOGKsdnI68q5YKYCKsK7XlIlZUHVlZ1HwafLkIom3P3OeFeWMiXwF+Vvvys3R8u9O/OgkxhS1vniQ== 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 Tue, 03 Oct 2023 19:01:45 +0200 "Arnd Bergmann" wrote: > On Tue, Oct 3, 2023, at 18:57, Arnd Bergmann wrote: > > On Tue, Oct 3, 2023, at 18:49, Andrew Morton wrote: > >> On Tue, 3 Oct 2023 10:48:56 -0400 Gregory Price > >> wrote: > >> > >>> do_pages_move does not handle compat pointers for the page list. > >>> correctly. Add in_compat_syscall check and appropriate get_user > >>> fetch when iterating the page list. > >> > >> What are the userspace visible effects of this change? > > > > It makes the syscall in compat mode (32-bit userspace, 64-bit kernel) > > work the same way as the native 32-bit syscall again, restoring the > > behavior before my broken commit 5b1b561ba73c ("mm: simplify > > compat_sys_move_pages"). > > More specifically, my patch moved the parsing of the 'pages' > array from the main entry point into do_pages_stat(), which left > the syscall working correctly for the 'stat' operation (nodes = NULL), > while the 'move' operation (nodes != NULL) is now missing > the conversion and interprets 'pages' as an array of 64-bit > pointers instead of the intended 32-bit userspace pointers. > Thanks. So is a cc:stable warranted?