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Thu, 6 Nov 2025 21:02:25 +1100 (AEDT) From: =?utf-8?q?Thomas_Wei=C3=9Fschuh?= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1762423341; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0B7YkbPIlqSoj0P/D9keGEmA0f3ObTbURi5IRJM/pXM=; b=rTh5AzdOU4DHUsOMOnWbiDWfL+4uyMkWzQgAbfZJ/px5TRTZrNIDTQ5TTeK8j5rPXyufjB H7bJxlpK0rm++C8qmfPXxkLG8FHTqSD/zhELreQ8T5p9Q0cQzt6wK/V0m3dogQOnP0FbM/ 9RT3T3flvAyDs4KhiCsPF6GFdy5X0mw9oMNr4mJsaBvWQyZm6B0gkSIdvw61yN8+rF6Rbj 1nT3gT3985ewGn28YEFcGRHfNqjlQDTsvwTd0hf1tBvbJ/fRUFKilM698gBsGW0yi4YU5X B0swcNGWJWJmvRw2ZaaNfivFyarRe2OUT5yQFYyN+MysxmiWwO96f+zE3OLJEw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1762423341; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=0B7YkbPIlqSoj0P/D9keGEmA0f3ObTbURi5IRJM/pXM=; b=Qr5vrwnEGTdXs43qwnoObu1jc0kRTBtVkpX/f4DQRjZTbZ71sg8u8jsQ+r2waidhpAyRu1 zkcorxtbtUVF0cBA== Date: Thu, 06 Nov 2025 11:02:12 +0100 Subject: [PATCH v5 19/34] random: vDSO: only access vDSO datapage after random_init() X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , List-Unsubscribe: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20251106-vdso-sparc64-generic-2-v5-19-97ff2b6542f7@linutronix.de> References: <20251106-vdso-sparc64-generic-2-v5-0-97ff2b6542f7@linutronix.de> In-Reply-To: <20251106-vdso-sparc64-generic-2-v5-0-97ff2b6542f7@linutronix.de> To: Andy Lutomirski , Thomas Gleixner , Vincenzo Frascino , Arnd Bergmann , "David S. Miller" , Andreas Larsson , Nick Alcock , John Stultz , Stephen Boyd , John Paul Adrian Glaubitz , Shuah Khan , Catalin Marinas , Will Deacon , Theodore Ts'o , "Jason A. Donenfeld" , Russell King , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , Christophe Leroy , Huacai Chen , WANG Xuerui , Thomas Bogendoerfer , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Shannon Nelson Cc: linux-kernel@vger.kernel.org, sparclinux@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-s390@vger.kernel.org, =?utf-8?q?Thomas_Wei=C3=9Fschuh?= X-Developer-Signature: v=1; a=ed25519-sha256; t=1762423327; l=2362; i=thomas.weissschuh@linutronix.de; s=20240209; h=from:subject:message-id; bh=nnfqDyJKV+11Uo9x3MwHeHQO2C8dr6iNLVlc2B+leBE=; b=fzvKWRUnoil/U9ov/twv/xZgHPWkat/4jEO7Y/mddE/lMWOXMPgXrZ9vAOtQgKUINpEmg86lw xRYdU4WoK0QCIy9rphUvPkmLQd9Dh8lWklVauD+6cPeh6xhrswM7tuq X-Developer-Key: i=thomas.weissschuh@linutronix.de; a=ed25519; pk=pfvxvpFUDJV2h2nY0FidLUml22uGLSjByFbM6aqQQws= Upcoming changes to the generic vDSO library will mean that the vDSO datapage will not yet be usable during early boot. Introduce a static key which prevents early accesses. Signed-off-by: Thomas Weißschuh Tested-by: Andreas Larsson Reviewed-by: Andreas Larsson --- drivers/char/random.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 73c53a4fb949bfd2ed723fa3cec3fe0d066a7fa3..f39524fb076a0c77bab228d4f2d45fee37291eb0 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -88,6 +88,7 @@ static DEFINE_STATIC_KEY_FALSE(crng_is_ready); static DECLARE_WAIT_QUEUE_HEAD(crng_init_wait); static struct fasync_struct *fasync; static ATOMIC_NOTIFIER_HEAD(random_ready_notifier); +static DEFINE_STATIC_KEY_FALSE(random_vdso_is_ready); /* Control how we warn userspace. */ static struct ratelimit_state urandom_warning = @@ -252,6 +253,9 @@ static void random_vdso_update_generation(unsigned long next_gen) if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM)) return; + if (!static_branch_likely(&random_vdso_is_ready)) + return; + /* base_crng.generation's invalid value is ULONG_MAX, while * vdso_k_rng_data->generation's invalid value is 0, so add one to the * former to arrive at the latter. Use smp_store_release so that this @@ -274,6 +278,9 @@ static void random_vdso_set_ready(void) if (!IS_ENABLED(CONFIG_VDSO_GETRANDOM)) return; + if (!static_branch_likely(&random_vdso_is_ready)) + return; + WRITE_ONCE(vdso_k_rng_data->is_ready, true); } @@ -925,6 +932,9 @@ void __init random_init(void) _mix_pool_bytes(&entropy, sizeof(entropy)); add_latent_entropy(); + if (IS_ENABLED(CONFIG_VDSO_GETRANDOM)) + static_branch_enable(&random_vdso_is_ready); + /* * If we were initialized by the cpu or bootloader before jump labels * or workqueues are initialized, then we should enable the static @@ -934,8 +944,10 @@ void __init random_init(void) crng_set_ready(NULL); /* Reseed if already seeded by earlier phases. */ - if (crng_ready()) + if (crng_ready()) { crng_reseed(NULL); + random_vdso_set_ready(); + } WARN_ON(register_pm_notifier(&pm_notifier)); -- 2.51.0