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 46CB919D8BC; Sat, 12 Sep 2026 10:38:34 +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=1789209515; cv=none; b=uKqTm7QClFpxyqOFwAQNKydXoezgFvk2r/dNU6cUFKv4Y5YBctrEsomJc8jIICjkPtYEtOJBjkgc8UrqNNHVfgbZp/YUS1LGgNQC1zrXd3CzdExe+q4Q6RFoWOWlQNivdYARvx3OcM4NrCpmdDsB48ZTr3g0Hlg8pdDf15VYuD8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789209515; c=relaxed/simple; bh=T7SPrJ8gve8obyUu0Sf0Pazssm4SSat1/sOw2LqVzOE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HhZSlUi2G+5vkH3FFU31F4IcRzsKGDuuvoFiAPrfK4KiFEpZAFKae2BN8wdflQwJmFKwgfIzDPki1JSC6cusGx70/3xG+w7HkjiSaGJ7UhNQ2KfPUc9sskdSEmmeqbakWyy2RpGGjRzuSJEWxx93EczgsiNdDogud+jGeztaC4Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DFPV4TW5; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="DFPV4TW5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00BD81F000FF; Sat, 12 Sep 2026 10:38:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789209514; bh=xVR6KWaEc6qQ7HI1jK3iehZrhulzzYAvDmjV17b/HTM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DFPV4TW5Ikckur5L5KDyv4PiliD/p4Llbf9stk2wt4vFf+89Fkua2rq69KSlehmm9 sfwFZZ2+WX46ydPquhrHuYVPAnHZdOaTGChOBdCwfbIakd4LqLJ/Ruy74An91jc39V yN6Ay3RoYWqC/t1TOp9/6QPglwOl/Ee2R/UUGi1Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Karl Mehltretter , Sasha Levin Subject: [PATCH 6.18 0837/1518] tty: clear cdev pointer after cdev_add() failure Date: Sat, 12 Sep 2026 08:50:06 +0200 Message-ID: <20260912065642.373561672@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065623.398859879@linuxfoundation.org> References: <20260912065623.398859879@linuxfoundation.org> User-Agent: quilt/0.69 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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Karl Mehltretter [ Upstream commit 6645856f0df3aeecd45519cb611415b4b89c2223 ] tty_cdev_add() drops the cdev reference when cdev_add() fails, but leaves driver->cdevs[index] pointing to freed memory. tty_unregister_device() later passes that stale pointer to cdev_del(), causing a use-after-free. Clear the slot after dropping the reference. Fixes: c1a752ba2d6b ("tty: don't leak cdev in tty_cdev_add()") Assisted-by: Claude:claude-fable-5 Signed-off-by: Karl Mehltretter Link: https://patch.msgid.link/20260731181844.11330-5-kmehltretter@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/tty/tty_io.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c index e2d92cf70eb78..f779f8fb138e8 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -3167,8 +3167,10 @@ static int tty_cdev_add(struct tty_driver *driver, dev_t dev, driver->cdevs[index]->ops = &tty_fops; driver->cdevs[index]->owner = driver->owner; err = cdev_add(driver->cdevs[index], dev, count); - if (err) + if (err) { kobject_put(&driver->cdevs[index]->kobj); + driver->cdevs[index] = NULL; + } return err; } -- 2.53.0