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([2a02:908:1b4:dac0:5d1e:7d5b:bff1:e1f7]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b8795a31322sm853009766b.63.2026.01.18.06.48.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 18 Jan 2026 06:48:08 -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] net: caif: fix memory leak in ldisc_receive Date: Sun, 18 Jan 2026 15:47:54 +0100 Message-ID: <20260118144800.18747-1-osama.abdelkader@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 netdev_alloc_skb() would allocate an skb, but if ser or ser->dev was NULL, the function would return early without freeing the allocated skb. Additionally, ser->dev was accessed before checking if it was NULL, which could cause a NULL pointer dereference. Reported-by: syzbot+f9d847b2b84164fa69f3@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Df9d847b2b84164fa69f3 Fixes: 9b27105b4a44 ("net-caif-driver: add CAIF serial driver (ldisc)") CC: stable@vger.kernel.org Signed-off-by: Osama Abdelkader --- drivers/net/caif/caif_serial.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/caif/caif_serial.c b/drivers/net/caif/caif_serial.c index c398ac42eae9..0ec9670bd35c 100644 --- a/drivers/net/caif/caif_serial.c +++ b/drivers/net/caif/caif_serial.c @@ -152,12 +152,16 @@ static void ldisc_receive(struct tty_struct *tty, con= st u8 *data, int ret; =20 ser =3D tty->disc_data; + if (!ser) + return; =20 /* * NOTE: flags may contain information about break or overrun. * This is not yet handled. */ =20 + if (!ser->dev) + return; =20 /* * Workaround for garbage at start of transmission, @@ -170,8 +174,6 @@ static void ldisc_receive(struct tty_struct *tty, const= u8 *data, return; } =20 - BUG_ON(ser->dev =3D=3D NULL); - /* Get a suitable caif packet and copy in data. */ skb =3D netdev_alloc_skb(ser->dev, count+1); if (skb =3D=3D NULL) --=20 2.43.0