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 EDE3B1C84BC; Wed, 8 Jul 2026 06:03:58 +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=1783490640; cv=none; b=JhRL75MyrjuVWG7Z6oPUj5bmEln8clOaqUlcFV9uQYOUgGqtA/lWe5+mXxw3XVWvX+opSn0Q30X9ebHCxKs8gM/y9/WBDBRu8p29y01T8rMU0EoNB8lcm1Kyh88Wb5Dx5wXH2fvY4dWzU192DjWzOJ6ytd7eRcqw8n9uh71tl/4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783490640; c=relaxed/simple; bh=GHGM6DdqMKYaVkNMvoYlLJ4JgEBlFHcA0prOojP0OkU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ZPYCx04qW7o1tLcqWB6BNUsVQEFhTIohUgG8/WxnDREulYNE+husF9WKMbBH1QwgBTLzVZzR88Et+6WZQMjULEguFBP3BsujP47ulyloQJbyeVL8trkmbNoqJHwYw2gH7HL5tpoybYDPYpALtoyyX4T5LbiTssbrX1A7cojLIs0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=N1czfc4x; 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="N1czfc4x" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 19AA31F000E9; Wed, 8 Jul 2026 06:03:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783490638; bh=krXgiCcw20UboyAFh1hr7VQZ/rEOaJ/YHz5XUVIESzY=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=N1czfc4x7LSbEyZQduOFeiSBGC2KjuVttAgUTnPlyzKf+Ljd+uFZ5ukQ2uXxq5E8I iZZP2ANSd2gOjYyzI+ijpUnScN+4lWL63ToiXtSZbpzDAJyXW5rbJrxq7wIlXLcE2g 1R1YxVe6Gd3r7EPaHYfEqeKwPBeiogx7wCdth0ia0ZwtbTUTvjqhLqdbo5UCrmmIiW 9ci87obv72Q5W/WmOZWHKkz/6TJ66R3DQksTZWvTM7kJwlKx3MG5ltDzOo5c3ffCQz JHOh9K9Gj4JMZ2IQBbnZ2URQvg49e9fetNIxzVxIVqg9s2iQhLZi08QIBAuuDubnZW DDkZwzWGuLTLA== Message-ID: <0ede8499-abe2-41d3-bb0c-095c02c5b699@kernel.org> Date: Wed, 8 Jul 2026 08:03:55 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6] serial: 8250: fix use-after-free in IRQ chain handling To: Qiliang Yuan , Greg Kroah-Hartman , Anton Vorontsov , Alan Cox Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Wang Zhaolong References: <20260707-bug-221579-8250-shared-irq-race-v6-1-f8c499a90bdd@gmail.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Ah, now I see you are fixing the same thing as: https://lore.kernel.org/all/20260708031115.3757150-1-wangzhaolong@fnnas.com/ I did not look up who of you was first. But: Reported-by: Wang Zhaolong Closes: https://bugzilla.kernel.org/show_bug.cgi?id=221579 Looks like he reported and apparently tries to fix that too ;). You were obviously CCed, talk to them and don't send two patches for the same issue. On 07. 07. 26, 16:06, Qiliang Yuan wrote: ... > --- a/drivers/tty/serial/8250/8250_core.c > +++ b/drivers/tty/serial/8250/8250_core.c > @@ -131,10 +131,11 @@ static void serial_do_unlink(struct irq_info *i, struct uart_8250_port *up) > * - allocate a new one, add it to the hashtable and return it. > */ > static struct irq_info *serial_get_or_create_irq_info(const struct uart_8250_port *up) > + __must_hold(&hash_mutex) > { > struct irq_info *i; > > - guard(mutex)(&hash_mutex); > + lockdep_assert_held(&hash_mutex); > > hash_for_each_possible(irq_lists, i, node, up->port.irq) > if (i->irq == up->port.irq) > @@ -151,19 +152,37 @@ static struct irq_info *serial_get_or_create_irq_info(const struct uart_8250_por > return i; > } > > +/* > + * serial_link_irq_chain() hooks the given 8250 port into the IRQ chain. > + * > + * hash_mutex must be held from the hash lookup through the first > + * request_irq() completion. Dropping it earlier allows a concurrent > + * serial_unlink_irq_chain() to race in after i->head is published but > + * before the IRQ is fully set up — another port sharing the IRQ can then > + * join the chain and run the shared-IRQ THRE test while IRQ startup is > + * still in progress, triggering an "Unbalanced enable for IRQ" warning > + * in kernel/irq/manage.c. > + */ > static int serial_link_irq_chain(struct uart_8250_port *up) > { > struct irq_info *i; > int ret; > > + guard(mutex)(&hash_mutex); hash_mutex is no longer an appropriate name for this lock. > + > i = serial_get_or_create_irq_info(up); > if (IS_ERR(i)) > return PTR_ERR(i); > > + /* > + * Serialise against the list manipulation in the interrupt handler > + * and in serial_unlink_irq_chain(). hash_mutex is still held which > + * prevents serial_unlink_irq_chain() from entering and freeing the > + * irq_info until the first request_irq() completes. > + */ > scoped_guard(spinlock_irq, &i->lock) { > if (i->head) { > list_add(&up->list, i->head); > - Unrelated change. > return 0; > } > > @@ -171,11 +190,14 @@ static int serial_link_irq_chain(struct uart_8250_port *up) > i->head = &up->list; > } > > - ret = request_irq(up->port.irq, serial8250_interrupt, up->port.irqflags, up->port.name, i); > - if (ret < 0) > + ret = request_irq(up->port.irq, serial8250_interrupt, > + up->port.irqflags, up->port.name, i); > + if (ret < 0) { > serial_do_unlink(i, up); > + return ret; > + } > > - return ret; > + return 0; Unrelated and mainly unneeded change. thanks, -- js suse labs