Re: kernel NULL pointer dereference, ucsi bug

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Mon, Jun 10, 2019 at 04:32:47PM +0200, Greg KH wrote:
> On Fri, Jun 07, 2019 at 02:58:51AM +1000, Vladimir Yerilov wrote:
> > Finally I can name the first bad commit:
> > 
> > git bisect good
> > ad74b8649beaf1a22cf8641324e3321fa0269d16 is the first bad commit
> > commit ad74b8649beaf1a22cf8641324e3321fa0269d16
> > Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> > Date:   Tue Apr 23 17:21:48 2019 +0300
> > 
> >    usb: typec: ucsi: Preliminary support for alternate modes
> > 
> >    With UCSI the alternate modes, just like everything else
> >    related to USB Type-C connectors, are handled in firmware.
> >    The operating system can see the status and is allowed to
> >    request certain things, for example entering and exiting the
> >    modes, but the support for alternate modes is very limited
> >    in UCSI. The feature is also optional, which means that even
> >    when the platform supports alternate modes, the operating
> >    system may not be even made aware of them.
> > 
> >    UCSI does not support direct VDM reading or writing.
> >    Instead, alternate modes can be entered and exited using a
> >    single custom command which takes also an optional SVID
> >    specific configuration value as parameter. That means every
> >    supported alternate mode has to be handled separately in
> >    UCSI driver.
> > 
> >    This commit does not include support for any specific
> >    alternate mode. The discovered alternate modes are now
> >    registered, but binding a driver to an alternate mode will
> >    not be possible until support for that alternate mode is
> >    added to the UCSI driver.
> > 
> >    Tested-by: Ajay Gupta <ajayg@nvidia.com>
> >    Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
> >    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > 
> > :040000 040000 f19a610d131d6d3e6397934562dd6112e78b2415
> > 76df0e463eeacf57157adba0291fc9577c7d5145 M      dr
> > ivers
> > 
> > git bisect log
> > git bisect start
> > # bad: [132d68d37d33f1d0b9c1f507c8b4d64c27ecec8a] Merge tag
> > 'usb-5.2-rc1' of git://git.kernel.org/pub/scm/
> > linux/kernel/git/gregkh/usb
> > git bisect bad 132d68d37d33f1d0b9c1f507c8b4d64c27ecec8a
> > # good: [86dc59e39031fb0d366d5b1f92db015b24bef70b] net: dsa: sja1105:
> > Make 'sja1105et_regs' and 'sja1105pq
> > rs_regs' static
> > git bisect good 86dc59e39031fb0d366d5b1f92db015b24bef70b
> > # good: [80f232121b69cc69a31ccb2b38c1665d770b0710] Merge
> > git://git.kernel.org/pub/scm/linux/kernel/git/dav
> > em/net-next
> > git bisect good 80f232121b69cc69a31ccb2b38c1665d770b0710
> > # good: [5d438e200215f61ca6a7aa69f3c4e035ac54d8ee] usb: typec: ucsi:
> > ccg: add get_fw_info function
> > git bisect good 5d438e200215f61ca6a7aa69f3c4e035ac54d8ee
> > # bad: [6f6a407a591ebe3e4c6bd2329b29862b3980a3ca] Merge tag
> > 'usb-serial-5.2-rc1' of https://git.kernel.org
> > /pub/scm/linux/kernel/git/johan/usb-serial into usb-next
> > git bisect bad 6f6a407a591ebe3e4c6bd2329b29862b3980a3ca
> > # bad: [e823d948b7e53dc982c867ac4ce7877fc0418897] usb: musb: dsps: Use
> > dev_get_drvdata()
> > git bisect bad e823d948b7e53dc982c867ac4ce7877fc0418897
> > # bad: [6fee3787ea7aebf25fecdce325ee9b2150c5727b] dt-bindings:
> > usb-xhci: Add r8a774c0 support
> > git bisect bad 6fee3787ea7aebf25fecdce325ee9b2150c5727b
> > # bad: [cf28369c634fafb5f4e81750cba6988cdb4b4490] usb: typec: Add
> > driver for NVIDIA Alt Modes
> > git bisect bad cf28369c634fafb5f4e81750cba6988cdb4b4490
> > # bad: [ad74b8649beaf1a22cf8641324e3321fa0269d16] usb: typec: ucsi:
> > Preliminary support for alternate mode
> > s
> > git bisect bad ad74b8649beaf1a22cf8641324e3321fa0269d16
> > # good: [5c9ae5a87573d38cfc4c740aafda2fa6ce06e401] usb: typec: ucsi:
> > ccg: add firmware flashing support
> > git bisect good 5c9ae5a87573d38cfc4c740aafda2fa6ce06e401
> > # first bad commit: [ad74b8649beaf1a22cf8641324e3321fa0269d16] usb:
> > typec: ucsi: Preliminary support for a
> > lternate modes
> > 
> > Best regards,
> > Vladimir
> 
> 
> Heikki, any thoughts?

I'll take a look.

> Vladimir, can you post the oops message again?  I don't see it here in
> the email thread anymore.
> 
> thanks,
> 
> greg k-h

thanks,

-- 
heikki