From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.tkos.co.il (guitar.tkos.co.il [84.110.109.230]) (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 AF6B135975; Mon, 22 Dec 2025 05:50:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=84.110.109.230 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766382604; cv=none; b=qYnHn7cjvqVflcB26zpq53gy4h1Qtc1oED5CXMeG6OeFVdHrinVfIsBxtLRdN8e6ShtS+TMK5ihHywoXLH9GEM3yvPhBXsCHAtEg/JDmHxJv0NFNeTfnNOLsNc/+2VdbAAggJMA0Mt6X7LIpZ+yXENawrpXNJGesBJOztv+nVAc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766382604; c=relaxed/simple; bh=I2mkLsR9R8yTlZ2vB9UNyIEZQCNZVBLCZLhYW9lMQ5Q=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=uzAltXko+OYe1UTT1HsQpm0tfv0Tl5exNPn4fGDTMD2RBZmVmp8g/ZmM45OJP2esR+Bul3AbZzxCStnN1AmY24fQc4ZMrKSneS5Rvkta8xtSGSJbU6Y1vNVfl3TyWp4coL1UxuV8GjJzDiqTiqJ5a+ZJ1gp4W3IvuyyWzw/PD5w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=tkos.co.il; spf=pass smtp.mailfrom=tkos.co.il; dkim=pass (2048-bit key) header.d=tkos.co.il header.i=@tkos.co.il header.b=VD0kIW9b; arc=none smtp.client-ip=84.110.109.230 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=tkos.co.il Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=tkos.co.il Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=tkos.co.il header.i=@tkos.co.il header.b="VD0kIW9b" Received: from localhost (unknown [10.0.8.3]) by mail.tkos.co.il (Postfix) with ESMTP id 9A1BC44064C; Mon, 22 Dec 2025 07:39:12 +0200 (IST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=tkos.co.il; s=default; t=1766381952; bh=I2mkLsR9R8yTlZ2vB9UNyIEZQCNZVBLCZLhYW9lMQ5Q=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=VD0kIW9bMDzR1OMZfs9Goe09MTNKkIU7dnzcp4vobqu8OiZNHQ/iMj+K3yxL+GMiu Bpnx6BUduJxcLvZZSRNR9JNQgvENQNCY+WSdEaLPpkEUCbD9CDbKNcD+fd2pFdGFhG 6lmx7iUql3OOZaa07CD9E90yyq+4KIvgKdvbcvspf4ovshofwwmB0UL79YyuXZoSjv bPmPMyOnq64bUao+pCUqw/r4LDmaHu/GbaW46PM04M8TssPQeCtpNzWDe0weAsHdoJ KGIGk2aNpp43cOdnnMBDbeKp/eKKkuXXEO5JUc0J08HRzbm8NC8D+M7nYCwLPQAp1h Q3EW7yhhTOYFg== From: Baruch Siach To: Junrui Luo Cc: Greg Kroah-Hartman , Jiri Slaby , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Yuhao Jiang Subject: Re: [PATCH] serial: digicolor: fix use-after-free on driver unbind In-Reply-To: (Junrui Luo's message of "Mon, 22 Dec 2025 12:55:02 +0800") References: User-Agent: mu4e 1.12.13; emacs 30.2 Date: Mon, 22 Dec 2025 07:41:46 +0200 Message-ID: <871pkndqed.fsf@tarshish> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Hi Junrui, On Mon, Dec 22 2025, Junrui Luo wrote: > The digicolor_uart_console_write() function accesses the global > digicolor_ports[] array to retrieve the uart port pointer, which > can lead to a use-after-free if the console write occurs after > the port has been removed via unbind. > > digicolor_uart_remove() leaves a dangling pointer in the array. > > Fix by clearing the array entry in digicolor_uart_remove() and > adding a NULL check in digicolor_uart_console_write(). Thanks for the patch. Is this .write/.remove callbacks race actually possible? Can you refer me to similar fixes in other drivers? > Reported-by: Yuhao Jiang Where can I find this report? Thanks, baruch > Reported-by: Junrui Luo > Fixes: 5930cb3511df ("serial: driver for Conexant Digicolor USART") > Signed-off-by: Junrui Luo > --- > drivers/tty/serial/digicolor-usart.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/tty/serial/digicolor-usart.c b/drivers/tty/serial/digicolor-usart.c > index d2482df5cb9b..5861be2072c4 100644 > --- a/drivers/tty/serial/digicolor-usart.c > +++ b/drivers/tty/serial/digicolor-usart.c > @@ -397,6 +397,9 @@ static void digicolor_uart_console_write(struct console *co, const char *c, > unsigned long flags; > int locked = 1; > > + if (!port) > + return; > + > if (oops_in_progress) > locked = uart_port_trylock_irqsave(port, &flags); > else > @@ -508,6 +511,7 @@ static void digicolor_uart_remove(struct platform_device *pdev) > struct uart_port *port = platform_get_drvdata(pdev); > > uart_remove_one_port(&digicolor_uart, port); > + digicolor_ports[port->line] = NULL; > } > > static const struct of_device_id digicolor_uart_dt_ids[] = { > > --- > base-commit: ea1013c1539270e372fc99854bc6e4d94eaeff66 > change-id: 20251222-fixes-74e6b26513d1 > > Best regards, -- ~. .~ Tk Open Systems =}------------------------------------------------ooO--U--Ooo------------{= - baruch@tkos.co.il - tel: +972.52.368.4656, http://www.tkos.co.il -