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 7DC4A2C08D0; Sat, 12 Sep 2026 18:58:01 +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=1789239482; cv=none; b=nKiXprS8s0YH8KYUgZux6x1c7Uv06+E9YIbMuBJEDZk9Z+GWdTuDCqk7xFzF5GW/QAygfuWprRZNf7FetzZNiKnr86UDKAwyK3wIV7i1tobPZtD0nH9ti/tG0k2wIiyBciC6STFpnLlEFihY7+nYB+avu/Vp084wIg20Gy95MHc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789239482; c=relaxed/simple; bh=8qhYQgDGcKibGkU154ZKovgUWDOXV2YDNL7tO5gAzAI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=a5yzSniFIC4GmkbuMKk4DLOo1cxFL0D6e7P/4dDmiKxIAMXPQwrg/+yosWl8EL87FWKOX4HRBIYhfmqNjHn7k1W9jL7Pl/S3irw0uSicqjJ4haE08xTEceC65rs05254+aC0Abc/hlliG+GDyTGU1hZshb+nR1IjMSk32nOmsQw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=zDXzk84g; 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="zDXzk84g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F5AF1F000FF; Sat, 12 Sep 2026 18:57:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789239481; bh=4wP7OPGdODUBZsDmuf6IF5eqfKvbyihtugdvscNxAN4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=zDXzk84gw2C35Sr0707tKpW1u+fAiUxuxHfpJBKSMrY1+IksDXTf76VnKihBGagMj Mjhy9U+i/GKel7hJdOuPe0+GQEE7A5w2KuvpqEBs4TvFSu1DhscbggrdF/kdGSwP0B Iz3+1dh3OJ+M6kxiukH8A/JVdROH8HqUNR0ufHy8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Karl Mehltretter , Sasha Levin Subject: [PATCH 5.15 671/935] tty: clear cdev pointer after cdev_add() failure Date: Sat, 12 Sep 2026 09:01:41 +0200 Message-ID: <20260912065542.232633906@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@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 5.15-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 d5191065b6e91..d63ab274ff4a2 100644 --- a/drivers/tty/tty_io.c +++ b/drivers/tty/tty_io.c @@ -3194,8 +3194,10 @@ 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