From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 6A2C42E7F1A; Thu, 3 Jul 2025 14:59:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751554746; cv=none; b=JISKf/JVWHlxoG3d/uLu3//xTRfpQ4ckWxU3qWI2Jw7kTXLkTxtc0mnLJhER+H3YwaP7cgIzAnjV55eWj0e7ZSabyl3GnI3GbTgd2Vo4jRZgPuOJy/EpryFPQmAqLjZK1enVMNTlfkCbnbtFp3jDaRNDrJaqhNk+pMv8FU89ZA0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751554746; c=relaxed/simple; bh=Ip+FwU08aYl+GBiKp7RlTxh8HqqDw6UbfdOvM6Pevrw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=m78Gu2tMgKNlWWugHbhWL0rw4XbHPMFt3RRftB8awVEqp9fhQcHuVrl4zvL9j+KaP55ZjT4RsyUc3FHVEEhqwhUsDoDlzSa+52EsnxK8i2sniEs6Z+FMReXtIwuOr2aQlZ5/iCaXuoyVm+9ALQU5sNBdN+rXaA19giflBXVu3oI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=K94iWRzH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="K94iWRzH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CEABAC4CEE3; Thu, 3 Jul 2025 14:59:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1751554746; bh=Ip+FwU08aYl+GBiKp7RlTxh8HqqDw6UbfdOvM6Pevrw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=K94iWRzH0vTX+0gC4Xm3KBLhGr6G6dmLQ8RUkhtEXZ+WxjA8mXN92lNR/BKEsjRjd DNAVh2axtlOrR1i/uUFpdhWqLWME+i1CZCJkbz2Ck6W+hcCzh101e2uaoBZ39H4vC2 0itk9T16+R+xOKf6Tgq7OpWxYesRElpRNvr40wkM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Jakub Lewalski , Elodie Decerle , Sasha Levin Subject: [PATCH 6.15 058/263] tty: serial: uartlite: register uart driver in init Date: Thu, 3 Jul 2025 16:39:38 +0200 Message-ID: <20250703144006.636878262@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250703144004.276210867@linuxfoundation.org> References: <20250703144004.276210867@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jakub Lewalski [ Upstream commit 6bd697b5fc39fd24e2aa418c7b7d14469f550a93 ] When two instances of uart devices are probing, a concurrency race can occur. If one thread calls uart_register_driver function, which first allocates and assigns memory to 'uart_state' member of uart_driver structure, the other instance can bypass uart driver registration and call ulite_assign. This calls uart_add_one_port, which expects the uart driver to be fully initialized. This leads to a kernel panic due to a null pointer dereference: [ 8.143581] BUG: kernel NULL pointer dereference, address: 00000000000002b8 [ 8.156982] #PF: supervisor write access in kernel mode [ 8.156984] #PF: error_code(0x0002) - not-present page [ 8.156986] PGD 0 P4D 0 ... [ 8.180668] RIP: 0010:mutex_lock+0x19/0x30 [ 8.188624] Call Trace: [ 8.188629] ? __die_body.cold+0x1a/0x1f [ 8.195260] ? page_fault_oops+0x15c/0x290 [ 8.209183] ? __irq_resolve_mapping+0x47/0x80 [ 8.209187] ? exc_page_fault+0x64/0x140 [ 8.209190] ? asm_exc_page_fault+0x22/0x30 [ 8.209196] ? mutex_lock+0x19/0x30 [ 8.223116] uart_add_one_port+0x60/0x440 [ 8.223122] ? proc_tty_register_driver+0x43/0x50 [ 8.223126] ? tty_register_driver+0x1ca/0x1e0 [ 8.246250] ulite_probe+0x357/0x4b0 [uartlite] To prevent it, move uart driver registration in to init function. This will ensure that uart_driver is always registered when probe function is called. Signed-off-by: Jakub Lewalski Signed-off-by: Elodie Decerle Link: https://lore.kernel.org/r/20250331160732.2042-1-elodie.decerle@nokia.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/serial/uartlite.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c index a41e7fc373b7c..39c1fd1ff9ced 100644 --- a/drivers/tty/serial/uartlite.c +++ b/drivers/tty/serial/uartlite.c @@ -880,16 +880,6 @@ static int ulite_probe(struct platform_device *pdev) pm_runtime_set_active(&pdev->dev); pm_runtime_enable(&pdev->dev); - if (!ulite_uart_driver.state) { - dev_dbg(&pdev->dev, "uartlite: calling uart_register_driver()\n"); - ret = uart_register_driver(&ulite_uart_driver); - if (ret < 0) { - dev_err(&pdev->dev, "Failed to register driver\n"); - clk_disable_unprepare(pdata->clk); - return ret; - } - } - ret = ulite_assign(&pdev->dev, id, res->start, irq, pdata); pm_runtime_mark_last_busy(&pdev->dev); @@ -929,16 +919,25 @@ static struct platform_driver ulite_platform_driver = { static int __init ulite_init(void) { + int ret; + + pr_debug("uartlite: calling uart_register_driver()\n"); + ret = uart_register_driver(&ulite_uart_driver); + if (ret) + return ret; pr_debug("uartlite: calling platform_driver_register()\n"); - return platform_driver_register(&ulite_platform_driver); + ret = platform_driver_register(&ulite_platform_driver); + if (ret) + uart_unregister_driver(&ulite_uart_driver); + + return ret; } static void __exit ulite_exit(void) { platform_driver_unregister(&ulite_platform_driver); - if (ulite_uart_driver.state) - uart_unregister_driver(&ulite_uart_driver); + uart_unregister_driver(&ulite_uart_driver); } module_init(ulite_init); -- 2.39.5