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 7DC3B35AC10 for ; Mon, 1 Jun 2026 14:46:58 +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=1780325219; cv=none; b=Qayjqz92qgnDVnVfl3Txvxj/n5U7iEfsKD1epLIN+4NNGFrtGEjmClGm7jiznabGmU8cVcX6OMjGzFUBN86xiKoZ8Z9jnOZJkfcK4Gpm0gueiQTmCG5S3hVs8/5PTzoEVzXrRp3dLfB4Avi1zQazVkp5yp1XOg0aRQB8BE0aFF8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780325219; c=relaxed/simple; bh=cmblam7K6agUgq7vkJIUslSVCxej/Wx3+QRq6TsEys4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=gYxxL61U1nbHj+m9L4gCH7gujeVT/BRSLWhBh2GMzkgoo5knaNXhx/16FhLK+gIoBGHm3g070hyiHUjCChmGBAkKIUHAiSMZ0Iw/2LNPU7Sh5RkPE1NisSggNIc2wfqFdVhOJ77XQ8cs9zxfyR5aDBTC5I0QwOXs4p2/iSa1oZo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Qas35+wO; 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="Qas35+wO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF4DF1F00898; Mon, 1 Jun 2026 14:46:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780325218; bh=M5Fpqfuw+65m/Q26Pg3TH3AWZSD9AXENG6vyJ8/QjAE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Qas35+wOqBii81rn3xlDLunk1X0ntyEWJe7ojplnzah1ecrKlo0AJhufVeh+O3uU8 WJ4G4PEZGOPwvxIgyFxDTHoca1BP/03TVkjqWiMFdM0K8O5RWfGtU+xn6+omoNsunj xMJFK+TYadQ2Ia9DF5xC6QQGF8t5ntBaxm2ZdFCdEObl1KWWK2jQIh76Pe4zGtJjD5 8ITQl38vcoL+TJHpG2/wOzJyMX2Sq4uUkFhagKfnn1ztSdtyuDweGqgJd9i7AvxRPW pGpC6IyzqIQWS9MLwbeH+3z7QUvFeCOmnyCYcmXQDy+X+3FRkBFizzcuDdUl5rtKE0 /ZFsk0HPbsf7A== 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 10:46:55 -0400 Message-ID: <20260601144655.887986-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260601144655.887986-1-sashal@kernel.org> References: <2026052830-amicably-spoon-d982@gregkh> <20260601144655.887986-1-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