From: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
To: Nishanth Menon <nm@ti.com>, Tero Kristo <kristo@kernel.org>,
Santosh Shilimkar <ssantosh@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, kernel@pengutronix.de,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: firmware: ti_sci: resource leak and use after free
Date: Thu, 16 Feb 2023 09:39:08 +0100 [thread overview]
Message-ID: <20230216083908.mvmydic5lpi3ogo7@pengutronix.de> (raw)
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Hello,
The ti_sci firmware driver (drivers/firmware/ti_sci.c) has a problem in
its remove callback. I didn't check it to an end and I also don't have
the needed hardware available to test, so take my diagnosis with a grain
of salt.
The problem is that if ti_sci_remove() is called while info->users is
non-zero it skips ti_sci_debugfs_destroy() and mbox_free_channel(),
however the device will be unbound after ti_sci_remove() completes and
(among other stuff) *info will be freed. (See platform_remove() in
drivers/base/platform.c.) However the debugfs entries stay available and
accessing them will access *info. Also info stays linked in ti_sci_list
and might be traversed there. Maybe similar problems can happen with the
unfreed mbox channels.
Fixing that requires (at least) that info stays around until it's
completely unreferenced. I don't know enough about the firmware
framework and the involved hardware to suggest a fix though.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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