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SubjectRe: [PATCH v3] char: tpm: Protect tpm_pm_suspend with locks
On Mon, Nov 28, 2022 at 08:56:51PM +0100, Jason A. Donenfeld wrote:
> From: Jan Dabros <jsd@semihalf.com>
>
> Currently tpm transactions are executed unconditionally in
> tpm_pm_suspend() function, which may lead to races with other tpm
> accessors in the system. Specifically, the hw_random tpm driver makes
> use of tpm_get_random(), and this function is called in a loop from a
> kthread, which means it's not frozen alongside userspace, and so can
> race with the work done during system suspend:
>
> [ 3.277834] tpm tpm0: tpm_transmit: tpm_recv: error -52
> [ 3.278437] tpm tpm0: invalid TPM_STS.x 0xff, dumping stack for forensics
> [ 3.278445] CPU: 0 PID: 1 Comm: init Not tainted 6.1.0-rc5+ #135
> [ 3.278450] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-20220807_005459-localhost 04/01/2014
> [ 3.278453] Call Trace:
> [ 3.278458] <TASK>
> [ 3.278460] dump_stack_lvl+0x34/0x44
> [ 3.278471] tpm_tis_status.cold+0x19/0x20
> [ 3.278479] tpm_transmit+0x13b/0x390
> [ 3.278489] tpm_transmit_cmd+0x20/0x80
> [ 3.278496] tpm1_pm_suspend+0xa6/0x110
> [ 3.278503] tpm_pm_suspend+0x53/0x80
> [ 3.278510] __pnp_bus_suspend+0x35/0xe0
> [ 3.278515] ? pnp_bus_freeze+0x10/0x10
> [ 3.278519] __device_suspend+0x10f/0x350
>
> Fix this by calling tpm_try_get_ops(), which itself is a wrapper around
> tpm_chip_start(), but takes the appropriate mutex.
>
> Signed-off-by: Jan Dabros <jsd@semihalf.com>
> Reported-by: Vlastimil Babka <vbabka@suse.cz>
> Tested-by: Jason A. Donenfeld <Jason@zx2c4.com>
> Tested-by: Vlastimil Babka <vbabka@suse.cz>
> Link: https://lore.kernel.org/all/c5ba47ef-393f-1fba-30bd-1230d1b4b592@suse.cz/
> Cc: stable@vger.kernel.org
> Fixes: e891db1a18bf ("tpm: turn on TPM on suspend for TPM 1.x")
> [Jason: reworked commit message, added metadata]
> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
> ---
> drivers/char/tpm/tpm-interface.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 1621ce818705..d69905233aff 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -401,13 +401,14 @@ int tpm_pm_suspend(struct device *dev)
> !pm_suspend_via_firmware())
> goto suspended;
>
> - if (!tpm_chip_start(chip)) {
> + rc = tpm_try_get_ops(chip);
> + if (!rc) {
> if (chip->flags & TPM_CHIP_FLAG_TPM2)
> tpm2_shutdown(chip, TPM2_SU_STATE);
> else
> rc = tpm1_pm_suspend(chip, tpm_suspend_pcr);
>
> - tpm_chip_stop(chip);
> + tpm_put_ops(chip);
> }
>
> suspended:
> --
> 2.38.1
>

Hi, sorry for the latency.

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko

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