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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1687171393; bh=rNx4yQtapdMWkWm5zVEcQQCg/oEtXvyrJkwZzYmhLMI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Hn+1/wvGz2kQ1r0hnhWdxirc86Sqru5w3MekuU6rUZ+4/Gcmt/r0tZ89hivcN9xaH TQv6AbHl70ydTw90wFcaClp5SY8gjVvshRn1ckkE2AITSLlWb62PLKx8tRA9ZG3BOM uWLdqmc0ecPxVEYqgFHJy6ZClpskfB9cm42eta3uMbWMFehAsN+zR8vUdAEmNLA7Kw vg/Mhe3TS0qD24tTgWylMHrB/swXlxbtwTgszTSfgR0RgAvTxiUF328YZ2CnekzEr4 QM6Zk0z2DsdHryzESshDBzuAFEly9wz/wE+COiKMsmLKbHf0IlNMSQT3CCdFgdZ+gy i3NgQVKYQ/1Pg== Date: Mon, 19 Jun 2023 11:43:08 +0100 From: Lee Jones To: dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/1] x86/mm/KASLR: Store pud_page_tramp into entry rather than page Message-ID: <20230619104308.GC1472962@google.com> References: <20230614163859.924309-1-lee@kernel.org> <20230614163859.924309-2-lee@kernel.org> <20230616170027.GM3635807@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230616170027.GM3635807@google.com> X-Rspamd-Queue-Id: 7FACC20012 X-Rspam-User: X-Stat-Signature: zjffi1ngafspccc4qx56umor39crra8i X-Rspamd-Server: rspam03 X-HE-Tag: 1687171395-480767 X-HE-Meta: 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 03xikGY7 brGFg1ct9D709dueDED6INimrneb5tzQgHHQdiVvhyBOw/wwAHXwHMbXcTPJxj/QCiokw3SOi+SwUd7U+/63+4BgQlw6M4WBeEGkBCiYiv8YCEdN4BWD11XQi/cYO51VsDh9OQvriY4zvj0Hn5STQ6JqqXM8iBt2opqI6CBAk7Uvy8aY/+nvUleRKdHkHjVV21e5fGwMqwdbHAR91bkIbuH/8yjTBet/V8kzFSZmuUYvvMy7bubES0YuIVp8q1JZRS7b3ydDfXpE1H8FTcSr2uTpTS33EXxDfwoUZNflQ82rXYeBW1b0OB7SzshsAQuRDf2cpCce6hy5BpBQR0G9w2nBx2ULWNdCo4/nojwnuLI4DMxF0rWjMYN+Adw== 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 Fri, 16 Jun 2023, Lee Jones wrote: > On Wed, 14 Jun 2023, Lee Jones wrote: > > > set_pgd() expects to be passed whole pages to operate on, whereas > > trampoline_pgd_entry is, as the name suggests, an entry. The > > ramifications for using set_pgd() here are that the following thread of > > execution will not only place the suggested value into the > > trampoline_pgd_entry (8-Byte globally stored [.bss]) variable, PTI will > > also attempt to replicate that value into the non-existent neighboring > > user page (located +4k away), leading to the corruption of other global > > [.bss] stored variables. > > > > Suggested-by: Dave Hansen > > Signed-off-by: Lee Jones > > --- > > arch/x86/mm/kaslr.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > Is there any more you need from me at this point? > > Would you like me to resubmit with the Fixes: tag applied, or is > someone happy to apply it on merge? Superstar, thanks Dave. -- Lee Jones [李琼斯]