From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f42.google.com (mail-ed1-f42.google.com [209.85.208.42]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A8952FCBF5 for ; Sun, 18 Jan 2026 17:45:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768758334; cv=none; b=DgICz2crxMfgR62veyE6GAbP5NlUTHD890mR86lAk6yRDhzl+vRRvZyhkHhHU+MzJ7rm0Snw8S9OLHG1t5SiK04EhPaMaHMeHq6z1URSysIVVypsIpPGuJT/q16SiqZ89xdQa2MVhuwdwGaDIjh+xp2Y2LodHdhG1pw2d7DIqvg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768758334; c=relaxed/simple; bh=VcjR+Y1iNWZSa1ZtxEzMaBCTuPx9pXxpzhpYI/x/o48=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=iTyTEcCP6sIffpLqSblZD7fGuYWEUPjT8SIjvgxiKNLwSvhRtYbU53v66PBolGZVUNs6rGeJBCN8Dg9JyYzBZXn0r3fCp8rtLIwg5olJk1lgDnj049Yu6oWfO6C1H5RwiKJhh3I2Cihto+/H+thPYLtYftOAZfyoa+9DBbNZLfk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=M3BA18oM; arc=none smtp.client-ip=209.85.208.42 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="M3BA18oM" Received: by mail-ed1-f42.google.com with SMTP id 4fb4d7f45d1cf-64b92abe63aso7085735a12.0 for ; Sun, 18 Jan 2026 09:45:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1768758330; x=1769363130; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=PbagKvzCIQaOeLMD21+nxd4UKX2WNLT5bVzVk/tS3pc=; b=M3BA18oMmjUmADEe403rh92JvTWHfJCcY48LxqKL1hxU/xNRYO4P1I+s+d5Kojjg/D hY0Ioo6uA5GwfHoMf1Q1llyfqbp/liVpI7OapIk5cmoxODPRxbD8G6FfNVUALCGE1LbB MDau6kmCzdF0ZVVVdOiFRX2bcCqlCQVhrVMZEr6POMGnbiICD62EO2dmcW8wLZPLW8ta /A/ETvbfyys1Er8ifMxG8rrXODPLxnRalcx6HSAjp2jaj3JLgZkiaFkMRHJ7LOWtNn/8 lG8xtzT6T0wPkQQrBecBuuBEwF0wXmwQapECu9MaMDOCNfIV5BG7Ms9Ohz9nxQapx2va Bz5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768758330; x=1769363130; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=PbagKvzCIQaOeLMD21+nxd4UKX2WNLT5bVzVk/tS3pc=; b=f0m9wubJvOsqcQJyDjOugeU8ipdOevuN7O8fpUx6XxO4e13kj/Rz3LPKPmHkChJb5p obJ1Pcu0OkVaaX7gWvIIa7P1aXRH1pUdL9HOZ4GOsbf7bp8CWzugTEHV+dBCDrcfuPC/ lt3WqliNqpEi6sdL/Z93hTsWU3Ig8JbR6JVCevSQZ8uE2YWgMUQ2iwFhW+/iG76zaCjm 8/mDEVlPquOzMu8BhNvkFe1XbK8DSkE6SU61d8tSSK2e+BM95pvLyrnLn/rkugiqOVsM j7KL88yfDdNjFRPF4k5YXGv/ay1jhi/bq0Okw8HLjLG3Yiig3j1r2wADgt6h+BRsGGd2 xUtg== X-Forwarded-Encrypted: i=1; AJvYcCUfECnFyfCqd9iG8yGxRoQP2taOIwOvWShrMbRv1mh+dO426ezBRr8nWuLPyn9wnWMfA1prbfQ=@vger.kernel.org X-Gm-Message-State: AOJu0Yw5CH9gDwgjD5x5MYt8eXaIrcqJBWVlffbHLcX8SxSfQwY1kuaG sNfRQ1zsvt+i5YutiVX7xYNafva8xjFsTkGfWeJfvjglEd9WZr4tM2R2 X-Gm-Gg: AY/fxX6UaeSfrUl+f0kqxAMrCCZoxLGuQAoj+SSoU7PTUQMs8SrCdtmwPFrANlukOdm 9884HHtSz0ugPyQi56ea0q2+aNfK5H8fJLiAuxBoAouoUhXL8KkseJt9UzWCz9u1WI0ka1ApXLC ZKUmKU01VpZQF1FCBY/uoTiRe7GxqQNY7Tzf+QQijddWACgAodD6aWjz3YVGXmfiy2vPMM01Oca 92tQHkJs3WKLPlEG3TUnvByIYPjxID8fLlsyiiNlOFeOigErZi4Uf0ZNTK8IwuhLBcp/SdyW2xj /gtvpJdsD01GPK2h8smTzsRPOGsY8xZBJOu4g3Sr9cbsAwvjegoHXURdx1rNI05LUE5OWCXOBfp WpwS1a1t2YPyjyzxBRD/UtVciPQ+f70Ttp4G5/uvzlYu06R1vhKU7+oEaFkOSZkA2Y+6IiHTVxC qlL35e7ZBwDTFWAw== X-Received: by 2002:a05:6402:3491:b0:64b:5562:c8f4 with SMTP id 4fb4d7f45d1cf-654524cf27fmr7018655a12.7.1768758330277; Sun, 18 Jan 2026 09:45:30 -0800 (PST) Received: from osama.. ([2a02:908:1b4:dac0:5466:5c6:1ae0:13b7]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-65452bce411sm8105189a12.7.2026.01.18.09.45.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 18 Jan 2026 09:45:28 -0800 (PST) From: Osama Abdelkader To: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Greg Kroah-Hartman , "Jiri Slaby (SUSE)" , Osama Abdelkader , Sjur Braendeland , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: syzbot+f9d847b2b84164fa69f3@syzkaller.appspotmail.com, stable@vger.kernel.org Subject: [PATCH v2] net: caif: fix memory leak in ldisc_receive Date: Sun, 18 Jan 2026 18:44:16 +0100 Message-ID: <20260118174422.10257-1-osama.abdelkader@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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); if (skb == NULL) @@ -355,11 +355,15 @@ static void ldisc_close(struct tty_struct *tty) { struct ser_device *ser = tty->disc_data; + if (!ser) + return; + tty_kref_put(ser->tty); spin_lock(&ser_lock); list_move(&ser->node, &ser_release_list); spin_unlock(&ser_lock); + tty->disc_data = NULL; schedule_work(&ser_release_work); } -- 2.43.0