diff mbox

tpm: Fix NULL pointer dereference in tpm_transmit()

Message ID 1530695020-21888-1-git-send-email-shirish.s@amd.com (mailing list archive)
State New, archived
Headers show

Commit Message

Shirish S July 4, 2018, 9:03 a.m. UTC
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(+)

Comments

Jason Gunthorpe July 4, 2018, 2:43 p.m. UTC | #1
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

It makes no sense to call something like tpm_unregister from shutdown.

Jason
Jarkko Sakkinen July 4, 2018, 5:13 p.m. UTC | #2
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?

/Jarkko
S, Shirish July 5, 2018, 3:59 a.m. UTC | #3
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
Jarkko Sakkinen July 5, 2018, 3:21 p.m. UTC | #4
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 <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

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
diff mbox

Patch

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;