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Date: Wed, 2 Mar 2022 21:03:15 -0500 From: Stefan Berger <stefanb@...ux.ibm.com> To: Vincent Whitchurch <vincent.whitchurch@...s.com>, Peter Huewe <peterhuewe@....de>, Jarkko Sakkinen <jarkko@...nel.org>, Jason Gunthorpe <jgg@...pe.ca> Cc: kernel@...s.com, linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 2/2] tpm: Fix crash on tmprm release On 6/15/21 05:14, Vincent Whitchurch wrote: > If the tpm_tis module is removed (or a system shutdown is triggered) > while the tpmrm device is use, the kernel crashes due to chip->ops being > NULL: > > # exec 3<>/dev/tpmrm0 > # rmmod tpm_tis > # exit > ================================================================== > BUG: KASAN: null-ptr-deref in tpm_chip_start+0x2d/0x120 [tpm] > Read of size 8 at addr 0000000000000060 by task sh/994 > > Call Trace: > kasan_report.cold.13+0x10f/0x111 > tpm_chip_start+0x2d/0x120 [tpm] > tpm2_del_space+0x2c/0xa0 [tpm] > tpmrm_release+0x3f/0x50 [tpm] > __fput+0x110/0x3c0 > task_work_run+0x94/0xd0 > do_exit+0x683/0x13e0 > do_group_exit+0x8b/0x140 > do_syscall_64+0x3c/0x80 > ================================================================== > > Fix this by making tpm2_del_space() use tpm_try_get_ops(). The latter > already includes the calls to tpm_chip_start() and tpm_chip_stop(). > > Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com> As a follow-up to this message here: https://lkml.org/lkml/2022/3/1/552 Tested-by: Stefan Berger <stefanb@...ux.ibm.com> > --- > drivers/char/tpm/tpm2-space.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c > index 784b8b3cb903..e1111261021f 100644 > --- a/drivers/char/tpm/tpm2-space.c > +++ b/drivers/char/tpm/tpm2-space.c > @@ -58,12 +58,10 @@ int tpm2_init_space(struct tpm_space *space, unsigned int buf_size) > > void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space) > { > - mutex_lock(&chip->tpm_mutex); > - if (!tpm_chip_start(chip)) { > + if (!tpm_try_get_ops(chip)) { > tpm2_flush_sessions(chip, space); > - tpm_chip_stop(chip); > + tpm_put_ops(chip); > } > - mutex_unlock(&chip->tpm_mutex); > kfree(space->context_buf); > kfree(space->session_buf); > }
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