From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B0EEB363C53 for ; Mon, 1 Jun 2026 13:51:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780321887; cv=none; b=h+VZmCg7GEauQLacQZsWr/JccXlL1CkbyU0i3sUR/Pqa11JCbeAaFkwL47U+/+VQz3O7SN7FCGCN4Y5K5oSfhB8/6COCtmPu89b6TDiz75xCdZ3atOOxscNk1E2k38BHVquWYU9OpYNJKQgd+L3SKersWh9HHi6jqOE6Jbr9GmU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780321887; c=relaxed/simple; bh=cmblam7K6agUgq7vkJIUslSVCxej/Wx3+QRq6TsEys4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=LnWTBO/8fopkG2AIoD1Yp0EevtssZr85oFk/N3oA5XAIdfAu+/Yv/y3+W6xSntYi4TeAnSZA84Qx940v1UTFOEBBkMb+n1YNWqMGkVMPgRR9cuzawYRBC2lzrsBDWx0Q/0MTvBip07x5xDByGDboaGpQ8qJD7kKhbbyPpjV2j8w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=URPS9OFP; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="URPS9OFP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 260021F00898; Mon, 1 Jun 2026 13:51:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780321886; bh=M5Fpqfuw+65m/Q26Pg3TH3AWZSD9AXENG6vyJ8/QjAE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=URPS9OFPkWzK2kmpiBJM0EhKJzkm4LQu3Y8bess27V31LC6OfEpjXaJf4zbweLj/5 shCkBFIxEVNk3Rj5cAO1N3WnggRR62l1XQEPPkf79Wo6LVG4/XiEWzHjG7Zy2C1zQ2 ms4+JZ6G0pyyfuMUmbkOSn90I4dlSKEX3ote1GaoZijWcfOpxLeFBE70nb8OzenlpE V7DCVjJ6QURXaULXtKFqOIHnpaiQplDz2hDRDMoyNqL/Tojmkvdpk+m7LlD+FpPJYt nx1qD1eJStiw7uuF4IUo8UJ5Y/y2o7WNguook20TIY3VmrZVIZ6WJBs2go2l6Z1Wbl xrNH4Ztn4tu/g== From: Sasha Levin To: stable@vger.kernel.org Cc: Abdurrahman Hussain , Guenter Roeck , Sasha Levin Subject: [PATCH 6.18.y 2/2] hwmon: (pmbus/adm1266) serialize NVMEM blackbox read with pmbus_lock Date: Mon, 1 Jun 2026 09:51:23 -0400 Message-ID: <20260601135123.797428-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260601135123.797428-1-sashal@kernel.org> References: <2026052830-amicably-spoon-d982@gregkh> <20260601135123.797428-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Abdurrahman Hussain [ Upstream commit 9f1dd8f9491eb840cbea7ffdf4cad031e25f8ae0 ] adm1266_nvmem_read() is the reg_read callback the NVMEM core invokes when userspace reads /sys/bus/nvmem/devices/.../nvmem on this chip. On the first byte of every read it does a memset of data->dev_mem, walks the device blackbox through adm1266_nvmem_read_blackbox() (which issues a chain of PMBus block transactions), and then memcpys the refreshed buffer out to userspace. None of that runs under pmbus_lock today. Two consequences: - The PMBus traffic the refresh issues is not serialised against pmbus_core's own multi-step PAGE+register sequences. A paged hwmon attribute read from another thread can land between a PAGE write and the paged read in either direction and corrupt one side's view of the device state machine. - The NVMEM core does not serialise concurrent reg_read calls, so two userspace readers racing at offset 0 can interleave the memset of data->dev_mem with another reader's adm1266_nvmem_read_blackbox() refill or memcpy out, returning torn data to userspace. Take pmbus_lock at the top of adm1266_nvmem_read() via the scope-based guard(). Patch 5 of this series moves adm1266_config_nvmem() past pmbus_do_probe() so the lock is guaranteed to be live before the callback is reachable from userspace. Fixes: 15609d189302 ("hwmon: (pmbus/adm1266) read blackbox") Cc: stable@vger.kernel.org Signed-off-by: Abdurrahman Hussain Link: https://lore.kernel.org/r/20260518-adm1266-gpio-fixes-v3-7-e425e4f88139@nexthop.ai Signed-off-by: Guenter Roeck Signed-off-by: Sasha Levin --- drivers/hwmon/pmbus/adm1266.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/hwmon/pmbus/adm1266.c b/drivers/hwmon/pmbus/adm1266.c index d90f8f80be8e0..3efa704410538 100644 --- a/drivers/hwmon/pmbus/adm1266.c +++ b/drivers/hwmon/pmbus/adm1266.c @@ -383,6 +383,8 @@ static int adm1266_nvmem_read(void *priv, unsigned int offset, void *val, size_t if (offset + bytes > data->nvmem_config.size) return -EINVAL; + guard(pmbus_lock)(data->client); + if (offset == 0) { memset(data->dev_mem, 0, data->nvmem_config.size); -- 2.53.0