From: Catalin Marinas <catalin.marinas@arm.com>
To: Samuel Holland <samuel.holland@sifive.com>
Cc: linux-arm-kernel@lists.infradead.org,
Andrew Morton <akpm@linux-foundation.org>,
Andrey Konovalov <andreyknvl@gmail.com>,
Ard Biesheuvel <ardb@kernel.org>,
Douglas Anderson <dianders@chromium.org>,
Frederic Weisbecker <frederic@kernel.org>,
James Morse <james.morse@arm.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Mark Rutland <mark.rutland@arm.com>,
Puranjay Mohan <puranjay@kernel.org>,
"Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
Ryo Takakura <takakura@valinux.co.jp>,
Shaoqin Huang <shahuang@redhat.com>,
Stephen Boyd <swboyd@chromium.org>,
Thomas Gleixner <tglx@linutronix.de>,
Will Deacon <will@kernel.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64: Fix KASAN random tag seed initialization
Date: Wed, 14 Aug 2024 17:18:56 +0100 [thread overview]
Message-ID: <ZrzY8Kk-1PwZlezI@arm.com> (raw)
In-Reply-To: <20240814091005.969756-1-samuel.holland@sifive.com>
On Wed, Aug 14, 2024 at 02:09:53AM -0700, Samuel Holland wrote:
> Currently, kasan_init_sw_tags() is called before setup_per_cpu_areas(),
> so per_cpu(prng_state, cpu) accesses the same address regardless of the
> value of "cpu", and the same seed value gets copied to the percpu area
> for every CPU. Fix this by moving the call to smp_prepare_boot_cpu(),
> which is the first architecture hook after setup_per_cpu_areas().
Even with the fix, given the lower resolution of get_cycles(), there's a
good chance that we still have the same seed on all CPUs. If we want
separate seeds, a better bet would be to initialise each CPU separately
via the secondary_start_kernel() path. I'll let the KASAN people comment
on whether that's important.
--
Catalin
next prev parent reply other threads:[~2024-08-14 16:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-08-14 9:09 [PATCH] arm64: Fix KASAN random tag seed initialization Samuel Holland
2024-08-14 16:04 ` Andrey Konovalov
2024-08-14 16:18 ` Catalin Marinas [this message]
2024-08-14 17:25 ` Andrey Konovalov
2024-08-15 10:07 ` Catalin Marinas
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