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Wed, 25 Feb 2026 17:36:58 -0800 (PST) Received: from I4-L-HQH5357-01.ad.psu.edu ([130.203.159.160]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-507451cda23sm6638401cf.18.2026.02.25.17.36.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Feb 2026 17:36:57 -0800 (PST) From: Shuangpeng Bai To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, linux-kernel@vger.kernel.org, hdanton@sina.com, vadim.fedorenko@linux.dev, simon.horman@kernel.org, Shuangpeng Bai Subject: [PATCH net v3 0/1] serial: caif: hold tty->link reference to avoid UAF in pty_write_room Date: Wed, 25 Feb 2026 20:36:41 -0500 Message-Id: X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Follow-up to the v2 discussion: further debugging shows the KASAN slab-use-after-free is triggered in pty_write_room(), and the faulting access is on tty->link->port. The report points to the peer access in pty_write_room(): tty_buffer_space_avail(tty->link->port); This patch holds an extra kref on tty->link for the lifetime of the caif_serial line discipline: get the reference in ldisc_open() and drop it in ser_release(), and also drop it on the ldisc_open() error path. Changes since v2: - Update the analysis: the observed UAF is on tty->link, not ser->tty. - Keep tty->link alive while the line discipline is active. Link: https://lore.kernel.org/all/20260215025141.1106576-1-shuangpeng.kernel@gmail.com/T/#maee804ef687b4442f18c74e8801f5cde421ab000 (v2 thread) Link: https://gist.github.com/shuangpengbai/c898debad6bdf170a84be7e6b3d8707f (reproducer) Shuangpeng Bai (1): serial: caif: hold tty->link reference in ldisc_open and ser_release drivers/net/caif/caif_serial.c | 3 +++ 1 file changed, 3 insertions(+) -- 2.34.1