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 CF5E428A72B; Mon, 19 Jan 2026 06:58:24 +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=1768805904; cv=none; b=TWJWOVyfuZJZQko95U41NmKVJFggIA8G/df65sogMzbyihGVKFgZKyqHN1SesSBBoKY5e8dFw7N0vf7ejULNHGhpPgeX9EEn6t6acDHxaUMGC1idgqhrLn0hbddwmL0NtYkDJzBhi4U/NyJJGmJK2CgkERdof59vZd1th5Q/aEM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768805904; c=relaxed/simple; bh=Qin/Cq4LI8Tf76hSE9SdisNwPce9efdvqoc1FgGdrI8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eyLOuf9gjVifSN4CdJ6PDyycmPzF3XBM5Jn9biCGylDacWFq3T/+37gAl19IIT4FbGVAtmHyaSapNPJv6ob1ZNtSr8+8RhIgGfu5YYGxo10vAhaA9oB4g1faoHCRj7838BYuqTEoy3mz2al28ku1eWUTX0MhMOxBDsKZTpnvvGo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YVEQ9HWY; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YVEQ9HWY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5687C116C6; Mon, 19 Jan 2026 06:58:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768805904; bh=Qin/Cq4LI8Tf76hSE9SdisNwPce9efdvqoc1FgGdrI8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=YVEQ9HWYGdTe1JYR1nh4DoRvVYJZoZoaEhJhIVfuasLgwhEmVWZN8kPT01C6BU25N 7aVX49VFWwHLLGa5qSJjIjXbtYXvIO493LBoOwSq/ZEbufR2kkQM5gkwh0t/MYMNyo bHLkUMEj96ANtgIZ2RxRNuPfdaG7mOsaZ46mN6Ryp2v8SzYV6iUwQRrqy0IKhhccjY LrLuD9/yD+05a4MN0+qzsXkqbWnyrCUEYKzVEOOH9gQiSqpufAUq5mOrh0wdnkxdlU 9QbjQcloTfJbqI8YxSrTM/r5VvfX1oWmva4ZxjK6Ln7VVbGjhVFEOU+LAqlbJ0PKKH +obITXZHDuIBA== Message-ID: <9a7c53ac-d208-457f-9940-ca821b08df1e@kernel.org> Date: Mon, 19 Jan 2026 07:58:19 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] net: caif: fix memory leak in ldisc_receive To: Osama Abdelkader , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Greg Kroah-Hartman , Sjur Braendeland , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: syzbot+f9d847b2b84164fa69f3@syzkaller.appspotmail.com, stable@vger.kernel.org References: <20260118174422.10257-1-osama.abdelkader@gmail.com> Content-Language: en-US From: Jiri Slaby Autocrypt: addr=jirislaby@kernel.org; keydata= xsFNBE6S54YBEACzzjLwDUbU5elY4GTg/NdotjA0jyyJtYI86wdKraekbNE0bC4zV+ryvH4j rrcDwGs6tFVrAHvdHeIdI07s1iIx5R/ndcHwt4fvI8CL5PzPmn5J+h0WERR5rFprRh6axhOk rSD5CwQl19fm4AJCS6A9GJtOoiLpWn2/IbogPc71jQVrupZYYx51rAaHZ0D2KYK/uhfc6neJ i0WqPlbtIlIrpvWxckucNu6ZwXjFY0f3qIRg3Vqh5QxPkojGsq9tXVFVLEkSVz6FoqCHrUTx wr+aw6qqQVgvT/McQtsI0S66uIkQjzPUrgAEtWUv76rM4ekqL9stHyvTGw0Fjsualwb0Gwdx ReTZzMgheAyoy/umIOKrSEpWouVoBt5FFSZUyjuDdlPPYyPav+hpI6ggmCTld3u2hyiHji2H cDpcLM2LMhlHBipu80s9anNeZhCANDhbC5E+NZmuwgzHBcan8WC7xsPXPaiZSIm7TKaVoOcL 9tE5aN3jQmIlrT7ZUX52Ff/hSdx/JKDP3YMNtt4B0cH6ejIjtqTd+Ge8sSttsnNM0CQUkXps w98jwz+Lxw/bKMr3NSnnFpUZaxwji3BC9vYyxKMAwNelBCHEgS/OAa3EJoTfuYOK6wT6nadm YqYjwYbZE5V/SwzMbpWu7Jwlvuwyfo5mh7w5iMfnZE+vHFwp/wARAQABzSFKaXJpIFNsYWJ5 IDxqaXJpc2xhYnlAa2VybmVsLm9yZz7CwXcEEwEIACEFAlW3RUwCGwMFCwkIBwIGFQgJCgsC BBYCAwECHgECF4AACgkQvSWxBAa0cEnVTg//TQpdIAr8Tn0VAeUjdVIH9XCFw+cPSU+zMSCH eCZoA/N6gitEcnvHoFVVM7b3hK2HgoFUNbmYC0RdcSc80pOF5gCnACSP9XWHGWzeKCARRcQR 4s5YD8I4VV5hqXcKo2DFAtIOVbHDW+0okOzcecdasCakUTr7s2fXz97uuoc2gIBB7bmHUGAH XQXHvdnCLjDjR+eJN+zrtbqZKYSfj89s/ZHn5Slug6w8qOPT1sVNGG+eWPlc5s7XYhT9z66E l5C0rG35JE4PhC+tl7BaE5IwjJlBMHf/cMJxNHAYoQ1hWQCKOfMDQ6bsEr++kGUCbHkrEFwD UVA72iLnnnlZCMevwE4hc0zVhseWhPc/KMYObU1sDGqaCesRLkE3tiE7X2cikmj/qH0CoMWe gjnwnQ2qVJcaPSzJ4QITvchEQ+tbuVAyvn9H+9MkdT7b7b2OaqYsUP8rn/2k1Td5zknUz7iF oJ0Z9wPTl6tDfF8phaMIPISYrhceVOIoL+rWfaikhBulZTIT5ihieY9nQOw6vhOfWkYvv0Dl o4GRnb2ybPQpfEs7WtetOsUgiUbfljTgILFw3CsPW8JESOGQc0Pv8ieznIighqPPFz9g+zSu Ss/rpcsqag5n9rQp/H3WW5zKUpeYcKGaPDp/vSUovMcjp8USIhzBBrmI7UWAtuedG9prjqfO wU0ETpLnhgEQAM+cDWLL+Wvc9cLhA2OXZ/gMmu7NbYKjfth1UyOuBd5emIO+d4RfFM02XFTI t4MxwhAryhsKQQcA4iQNldkbyeviYrPKWjLTjRXT5cD2lpWzr+Jx7mX7InV5JOz1Qq+P+nJW YIBjUKhI03ux89p58CYil24Zpyn2F5cX7U+inY8lJIBwLPBnc9Z0An/DVnUOD+0wIcYVnZAK DiIXODkGqTg3fhZwbbi+KAhtHPFM2fGw2VTUf62IHzV+eBSnamzPOBc1XsJYKRo3FHNeLuS8 f4wUe7bWb9O66PPFK/RkeqNX6akkFBf9VfrZ1rTEKAyJ2uqf1EI1olYnENk4+00IBa+BavGQ 8UW9dGW3nbPrfuOV5UUvbnsSQwj67pSdrBQqilr5N/5H9z7VCDQ0dhuJNtvDSlTf2iUFBqgk 3smln31PUYiVPrMP0V4ja0i9qtO/TB01rTfTyXTRtqz53qO5dGsYiliJO5aUmh8swVpotgK4 /57h3zGsaXO9PGgnnAdqeKVITaFTLY1ISg+Ptb4KoliiOjrBMmQUSJVtkUXMrCMCeuPDGHo7 39Xc75lcHlGuM3yEB//htKjyprbLeLf1y4xPyTeeF5zg/0ztRZNKZicgEmxyUNBHHnBKHQxz 1j+mzH0HjZZtXjGu2KLJ18G07q0fpz2ZPk2D53Ww39VNI/J9ABEBAAHCwV8EGAECAAkFAk6S 54YCGwwACgkQvSWxBAa0cEk3tRAAgO+DFpbyIa4RlnfpcW17AfnpZi9VR5+zr496n2jH/1ld wRO/S+QNSA8qdABqMb9WI4BNaoANgcg0AS429Mq0taaWKkAjkkGAT7mD1Q5PiLr06Y/+Kzdr 90eUVneqM2TUQQbK+Kh7JwmGVrRGNqQrDk+gRNvKnGwFNeTkTKtJ0P8jYd7P1gZb9Fwj9YLx jhn/sVIhNmEBLBoI7PL+9fbILqJPHgAwW35rpnq4f/EYTykbk1sa13Tav6btJ+4QOgbcezWI wZ5w/JVfEJW9JXp3BFAVzRQ5nVrrLDAJZ8Y5ioWcm99JtSIIxXxt9FJaGc1Bgsi5K/+dyTKL wLMJgiBzbVx8G+fCJJ9YtlNOPWhbKPlrQ8+AY52Aagi9WNhe6XfJdh5g6ptiOILm330mkR4g W6nEgZVyIyTq3ekOuruftWL99qpP5zi+eNrMmLRQx9iecDNgFr342R9bTDlb1TLuRb+/tJ98 f/bIWIr0cqQmqQ33FgRhrG1+Xml6UXyJ2jExmlO8JljuOGeXYh6ZkIEyzqzffzBLXZCujlYQ DFXpyMNVJ2ZwPmX2mWEoYuaBU0JN7wM+/zWgOf2zRwhEuD3A2cO2PxoiIfyUEfB9SSmffaK/ S4xXoB6wvGENZ85Hg37C7WDNdaAt6Xh2uQIly5grkgvWppkNy4ZHxE+jeNsU7tg= In-Reply-To: <20260118174422.10257-1-osama.abdelkader@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 18. 01. 26, 18:44, Osama Abdelkader wrote: > Add NULL pointer checks for ser and ser->dev in ldisc_receive() to > prevent memory leaks when the function is called during device close > or in race conditions where tty->disc_data or ser->dev may be NULL. > > The memory leak occurred because ser->dev was accessed before checking > if ser or ser->dev was NULL, which could cause a NULL pointer > dereference or use of freed memory. Additionally, set tty->disc_data > to NULL in ldisc_close() to prevent receive_buf() from using a freed > ser pointer after the line discipline is closed. > > Reported-by: syzbot+f9d847b2b84164fa69f3@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=f9d847b2b84164fa69f3 > Fixes: 9b27105b4a44 ("net-caif-driver: add CAIF serial driver (ldisc)") > CC: stable@vger.kernel.org > Signed-off-by: Osama Abdelkader > --- > v2: > 1.Combine NULL pointer checks for ser and ser->dev in ldisc_receive() > 2.Set tty->disc_data = NULL in ldisc_close() to prevent receive_buf() > from using a freed ser pointer after close. > 3.Add NULL pointer check for ser in ldisc_close() > --- > drivers/net/caif/caif_serial.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/caif/caif_serial.c b/drivers/net/caif/caif_serial.c > index c398ac42eae9..970237a3ccca 100644 > --- a/drivers/net/caif/caif_serial.c > +++ b/drivers/net/caif/caif_serial.c > @@ -152,6 +152,8 @@ static void ldisc_receive(struct tty_struct *tty, const u8 *data, > int ret; > > ser = tty->disc_data; > + if (!ser || !ser->dev) > + return; > > /* > * NOTE: flags may contain information about break or overrun. > @@ -170,8 +172,6 @@ static void ldisc_receive(struct tty_struct *tty, const u8 *data, > return; > } > > - BUG_ON(ser->dev == NULL); > - > /* Get a suitable caif packet and copy in data. */ > skb = netdev_alloc_skb(ser->dev, count+1); Wait, the reported error is memory leak of mem allocated here. So both ser and ser->dev appear to be valid? So instead, does netif_rx() return an error few lines below for some reason? So should skb just be freed in that path? if (skb == NULL) return; skb_put_data(skb, data, count); skb->protocol = htons(ETH_P_CAIF); skb_reset_mac_header(skb); debugfs_rx(ser, data, count); /* Push received packet up the stack. */ ret = netif_rx(skb); if (!ret) { ser->dev->stats.rx_packets++; ser->dev->stats.rx_bytes += count; } else ++ser->dev->stats.rx_dropped; Not calling skb_free() in this else path _is_ a BUG™ in any case IMO. thanks, -- js suse labs