LinuxLists.cc - [PATCH] tpm: Fix NULL pointer dereference in tpm

2018-07-04 09:05:35

Subject: [PATCH] tpm: Fix NULL pointer dereference in tpm_transmit()

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 <[email protected]>
---
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

2018-07-04 14:45:21

by Jason Gunthorpe

[permalink] [raw]

Subject: Re: [PATCH] tpm: Fix NULL pointer dereference in tpm_transmit()

2018-07-04 17:16:11

by Jarkko Sakkinen

[permalink] [raw]

Subject: Re: [PATCH] tpm: Fix NULL pointer dereference in tpm_transmit()

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 <[email protected]>
> ---
> 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

2018-07-05 03:51:34

by S, Shirish

[permalink] [raw]

Subject: Re: [PATCH] tpm: Fix NULL pointer dereference in tpm_transmit()

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 <[email protected]>
>> ---
>> 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

2018-07-05 15:24:35

by Jarkko Sakkinen

[permalink] [raw]

Subject: Re: [PATCH] tpm: Fix NULL pointer dereference in tpm_transmit()

On Thu, Jul 05, 2018 at 09:29:34AM +0530, S, Shirish wrote:
>
>
> 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 <[email protected]>
> > > ---
> > > 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

tpm_chip_unregister() in supposed to be called only in removal/detach
sequence so the root cause for the NULL pointer deref is the driver, not
the existing TPM stack.

/Jarkko