On Wed, Jul 04, 2018 at 02:33:40PM +0530, Shirish S wrote: > During system shutdown, > tpm_class_shutdown() when called with TPM_CHIP_FLAG_TPM2 > flag set, makes chip->ops NULL. > > However tpm_chip_unregister() called later in shutdown > sequence tries to access chip->ops in tpm_try_transmit() > leading the NULL pointer dereference. > > This patch fixes this issue. > Below is the trace for reference: > > BUG: unable to handle kernel NULL pointer dereference at > 0000000000000048 > IP: tpm_transmit+0x267/0x565 > PGD 0 P4D 0 > Oops: 0000 [#1] PREEMPT SMP NOPTI > ... > task: ffff937c847fe580 task.stack: ffffa79f80b04000 > RIP: 0010:tpm_transmit+0x267/0x565 > RSP: 0018:ffffa79f80b07c08 EFLAGS: 00010286 > RAX: 0000000000000000 RBX: ffff937ca9bc8000 RCX: ffff937c847fe580 > RDX: 0000000000000000 RSI: 0000000000000002 RDI: ffffffff98e3cd40 > RBP: ffffa79f80b07c88 R08: 000000000001fff4 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: ffffa79f80b07cd4 > R13: 000000000000008c R14: ffffffffffffffc3 R15: 0000000000000000 > FS: 00007ef31f747740(0000) GS:ffff937caed00000(0000) > knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000048 CR3: 00000001243d2000 CR4: 00000000001406e0 > Call Trace: > tpm_transmit_cmd+0x25/0x70 > tpm2_shutdown+0x69/0xa3 > ? __radix_tree_replace+0xd9/0x120 > ? idr_replace_ext+0x92/0xb6 > tpm_chip_unregister+0xaa/0xdb > cr50_i2c_shutdown+0x1e/0x41 > device_shutdown+0x157/0x193 > kernel_power_off+0x35/0x6e > SYSC_reboot+0x120/0x1a3 > ? do_writepages+0x36/0x6e > ? do_writepages+0x36/0x6e > ? sync_inodes_one_sb+0x17/0x17 > ? _raw_spin_unlock+0xe/0x20 > ? iput+0x87/0x1bd > do_syscall_64+0x64/0x72 > entry_SYSCALL_64_after_hwframe+0x3d/0xa2 > > Signed-off-by: Shirish S <shirish.s@xxxxxxx> > --- > drivers/char/tpm/tpm-interface.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c > index e32f6e8..b14d196 100644 > --- a/drivers/char/tpm/tpm-interface.c > +++ b/drivers/char/tpm/tpm-interface.c > @@ -411,6 +411,14 @@ static ssize_t tpm_try_transmit(struct tpm_chip *chip, > unsigned long stop; > bool need_locality; > > + /* chip->ops is made NULL in tpm_class_shutdown() > + * This case is hit when tpm_chip_unregister() is called post > + * tpm_class_shutdown(), hence exit early and return > + * transmit operation not permitted > + */ > + if (!chip->ops) > + return -EPERM; > + > rc = tpm_validate_command(chip, space, buf, bufsiz); > if (rc == -EINVAL) > return rc; > -- > 2.7.4 > What is cr50 anyway? /Jarkko
