Messages in this thread | | | Subject | Re: [PATCH] tpm: Fix NULL pointer dereference in tpm_transmit() | From | "S, Shirish" <> | Date | Thu, 5 Jul 2018 09:29:34 +0530 |
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On 7/4/2018 10:43 PM, Jarkko Sakkinen wrote: > 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@amd.com> >> --- >> 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? Please ignore this patch, i realised the cr50 is not yet upstreamed. Hence the issue lies in in cr50 and not tpm driver. Thanks. Regards, Shirish S > /Jarkko
-- Regards, Shirish S
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