Shuangpeng Bai 27e43356d0 serial: caif: hold tty->link reference in ldisc_open and ser_release ...

[ Upstream commit 288598d80a ]

A reproducer triggers a KASAN slab-use-after-free in pty_write_room()
when caif_serial's TX path calls tty_write_room(). The faulting access
is on tty->link->port.

Hold an extra kref on tty->link for the lifetime of the caif_serial line
discipline: get it in ldisc_open() and drop it in ser_release(), and
also drop it on the ldisc_open() error path.

With this change applied, the reproducer no longer triggers the UAF in
my testing.

Link: https://gist.github.com/shuangpengbai/c898debad6bdf170a84be7e6b3d8707f
Link: https://lore.kernel.org/netdev/20260301220525.1546355-1-shuangpeng.kernel@gmail.com
Fixes: e31d5a0594 ("caif: tty's are kref objects so take a reference")
Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://patch.msgid.link/20260306034006.3395740-1-shuangpeng.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

2026-03-25 11:08:27 +01:00

..

caif_serial.c

serial: caif: hold tty->link reference in ldisc_open and ser_release

2026-03-25 11:08:27 +01:00

caif_virtio.c

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Kconfig

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Makefile

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