<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/ptp, branch linux-5.4.y</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>ptp: Ensure info-&gt;enable callback is always set</title>
<updated>2025-03-13T11:43:11+00:00</updated>
<author>
<name>Thomas Weißschuh</name>
<email>linux@weissschuh.net</email>
</author>
<published>2025-01-23T07:22:40+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=fdc1e72487781dd7705bcbe30878bee7d5d1f3e8'/>
<id>fdc1e72487781dd7705bcbe30878bee7d5d1f3e8</id>
<content type='text'>
commit fd53aa40e65f518453115b6f56183b0c201db26b upstream.

The ioctl and sysfs handlers unconditionally call the -&gt;enable callback.
Not all drivers implement that callback, leading to NULL dereferences.
Example of affected drivers: ptp_s390.c, ptp_vclock.c and ptp_mock.c.

Instead use a dummy callback if no better was specified by the driver.

Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh &lt;linux@weissschuh.net&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Reviewed-by: Michal Swiatkowski &lt;michal.swiatkowski@linux.intel.com&gt;
Link: https://patch.msgid.link/20250123-ptp-enable-v1-1-b015834d3a47@weissschuh.net
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit fd53aa40e65f518453115b6f56183b0c201db26b upstream.

The ioctl and sysfs handlers unconditionally call the -&gt;enable callback.
Not all drivers implement that callback, leading to NULL dereferences.
Example of affected drivers: ptp_s390.c, ptp_vclock.c and ptp_mock.c.

Instead use a dummy callback if no better was specified by the driver.

Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Cc: stable@vger.kernel.org
Signed-off-by: Thomas Weißschuh &lt;linux@weissschuh.net&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Reviewed-by: Michal Swiatkowski &lt;michal.swiatkowski@linux.intel.com&gt;
Link: https://patch.msgid.link/20250123-ptp-enable-v1-1-b015834d3a47@weissschuh.net
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp: Fix error message on failed pin verification</title>
<updated>2024-07-05T07:08:11+00:00</updated>
<author>
<name>Karol Kolacinski</name>
<email>karol.kolacinski@intel.com</email>
</author>
<published>2024-06-04T12:05:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=f1a03799d8ce1882fd673fb8d1ba19e119f78133'/>
<id>f1a03799d8ce1882fd673fb8d1ba19e119f78133</id>
<content type='text'>
[ Upstream commit 323a359f9b077f382f4483023d096a4d316fd135 ]

On failed verification of PTP clock pin, error message prints channel
number instead of pin index after "pin", which is incorrect.

Fix error message by adding channel number to the message and printing
pin number instead of channel number.

Fixes: 6092315dfdec ("ptp: introduce programmable pins.")
Signed-off-by: Karol Kolacinski &lt;karol.kolacinski@intel.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Link: https://lore.kernel.org/r/20240604120555.16643-1-karol.kolacinski@intel.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 323a359f9b077f382f4483023d096a4d316fd135 ]

On failed verification of PTP clock pin, error message prints channel
number instead of pin index after "pin", which is incorrect.

Fix error message by adding channel number to the message and printing
pin number instead of channel number.

Fixes: 6092315dfdec ("ptp: introduce programmable pins.")
Signed-off-by: Karol Kolacinski &lt;karol.kolacinski@intel.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Link: https://lore.kernel.org/r/20240604120555.16643-1-karol.kolacinski@intel.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp: annotate data-race around q-&gt;head and q-&gt;tail</title>
<updated>2023-11-28T16:50:16+00:00</updated>
<author>
<name>Eric Dumazet</name>
<email>edumazet@google.com</email>
</author>
<published>2023-11-09T17:48:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=7ea0a719e5789f9d3890df730142670818079c55'/>
<id>7ea0a719e5789f9d3890df730142670818079c55</id>
<content type='text'>
[ Upstream commit 73bde5a3294853947252cd9092a3517c7cb0cd2d ]

As I was working on a syzbot report, I found that KCSAN would
probably complain that reading q-&gt;head or q-&gt;tail without
barriers could lead to invalid results.

Add corresponding READ_ONCE() and WRITE_ONCE() to avoid
load-store tearing.

Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Link: https://lore.kernel.org/r/20231109174859.3995880-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 73bde5a3294853947252cd9092a3517c7cb0cd2d ]

As I was working on a syzbot report, I found that KCSAN would
probably complain that reading q-&gt;head or q-&gt;tail without
barriers could lead to invalid results.

Add corresponding READ_ONCE() and WRITE_ONCE() to avoid
load-store tearing.

Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Signed-off-by: Eric Dumazet &lt;edumazet@google.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Link: https://lore.kernel.org/r/20231109174859.3995880-1-edumazet@google.com
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp_qoriq: fix memory leak in probe()</title>
<updated>2023-04-05T09:16:43+00:00</updated>
<author>
<name>SongJingyi</name>
<email>u201912584@hust.edu.cn</email>
</author>
<published>2023-03-24T03:14:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=46c4993a1514eea3bbc7147d0c81c23cc06c6bed'/>
<id>46c4993a1514eea3bbc7147d0c81c23cc06c6bed</id>
<content type='text'>
[ Upstream commit f33642224e38d7e0d59336e10e7b4e370b1c4506 ]

Smatch complains that:
drivers/ptp/ptp_qoriq.c ptp_qoriq_probe()
warn: 'base' from ioremap() not released.

Fix this by revising the parameter from 'ptp_qoriq-&gt;base' to 'base'.
This is only a bug if ptp_qoriq_init() returns on the
first -ENODEV error path.
For other error paths ptp_qoriq-&gt;base and base are the same.
And this change makes the code more readable.

Fixes: 7f4399ba405b ("ptp_qoriq: fix NULL access if ptp dt node missing")
Signed-off-by: SongJingyi &lt;u201912584@hust.edu.cn&gt;
Reviewed-by: Dan Carpenter &lt;error27@gmail.com&gt;
Reviewed-by: Dongliang Mu &lt;dzm91@hust.edu.cn&gt;
Link: https://lore.kernel.org/r/20230324031406.1895159-1-u201912584@hust.edu.cn
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit f33642224e38d7e0d59336e10e7b4e370b1c4506 ]

Smatch complains that:
drivers/ptp/ptp_qoriq.c ptp_qoriq_probe()
warn: 'base' from ioremap() not released.

Fix this by revising the parameter from 'ptp_qoriq-&gt;base' to 'base'.
This is only a bug if ptp_qoriq_init() returns on the
first -ENODEV error path.
For other error paths ptp_qoriq-&gt;base and base are the same.
And this change makes the code more readable.

Fixes: 7f4399ba405b ("ptp_qoriq: fix NULL access if ptp dt node missing")
Signed-off-by: SongJingyi &lt;u201912584@hust.edu.cn&gt;
Reviewed-by: Dan Carpenter &lt;error27@gmail.com&gt;
Reviewed-by: Dongliang Mu &lt;dzm91@hust.edu.cn&gt;
Link: https://lore.kernel.org/r/20230324031406.1895159-1-u201912584@hust.edu.cn
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp: replace snprintf with sysfs_emit</title>
<updated>2022-04-15T12:18:32+00:00</updated>
<author>
<name>Yang Guang</name>
<email>yang.guang5@zte.com.cn</email>
</author>
<published>2022-01-27T00:02:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=9388d876099710da96a0e64b512b08c019d7fc19'/>
<id>9388d876099710da96a0e64b512b08c019d7fc19</id>
<content type='text'>
[ Upstream commit e2cf07654efb0fd7bbcb475c6f74be7b5755a8fd ]

coccinelle report:
./drivers/ptp/ptp_sysfs.c:17:8-16:
WARNING: use scnprintf or sprintf
./drivers/ptp/ptp_sysfs.c:390:8-16:
WARNING: use scnprintf or sprintf

Use sysfs_emit instead of scnprintf or sprintf makes more sense.

Reported-by: Zeal Robot &lt;zealci@zte.com.cn&gt;
Signed-off-by: Yang Guang &lt;yang.guang5@zte.com.cn&gt;
Signed-off-by: David Yang &lt;davidcomponentone@gmail.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit e2cf07654efb0fd7bbcb475c6f74be7b5755a8fd ]

coccinelle report:
./drivers/ptp/ptp_sysfs.c:17:8-16:
WARNING: use scnprintf or sprintf
./drivers/ptp/ptp_sysfs.c:390:8-16:
WARNING: use scnprintf or sprintf

Use sysfs_emit instead of scnprintf or sprintf makes more sense.

Reported-by: Zeal Robot &lt;zealci@zte.com.cn&gt;
Signed-off-by: Yang Guang &lt;yang.guang5@zte.com.cn&gt;
Signed-off-by: David Yang &lt;davidcomponentone@gmail.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp_pch: Load module automatically if ID matches</title>
<updated>2021-10-13T08:08:19+00:00</updated>
<author>
<name>Andy Shevchenko</name>
<email>andriy.shevchenko@linux.intel.com</email>
</author>
<published>2021-10-01T16:20:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=27e53e23a3cef73a6aac9a776685af1bebca0565'/>
<id>27e53e23a3cef73a6aac9a776685af1bebca0565</id>
<content type='text'>
[ Upstream commit 7cd8b1542a7ba0720c5a0a85ed414a122015228b ]

The driver can't be loaded automatically because it misses
module alias to be provided. Add corresponding MODULE_DEVICE_TABLE()
call to the driver.

Fixes: 863d08ece9bf ("supports eg20t ptp clock")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 7cd8b1542a7ba0720c5a0a85ed414a122015228b ]

The driver can't be loaded automatically because it misses
module alias to be provided. Add corresponding MODULE_DEVICE_TABLE()
call to the driver.

Fixes: 863d08ece9bf ("supports eg20t ptp clock")
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp_pch: Restore dependency on PCI</title>
<updated>2021-08-26T12:36:17+00:00</updated>
<author>
<name>Andy Shevchenko</name>
<email>andriy.shevchenko@linux.intel.com</email>
</author>
<published>2021-08-13T17:33:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c9566df334d0c3356c80b9ba79161ebb433c16c6'/>
<id>c9566df334d0c3356c80b9ba79161ebb433c16c6</id>
<content type='text'>
[ Upstream commit 55c8fca1dae1fb0d11deaa21b65a647dedb1bc50 ]

During the swap dependency on PCH_GBE to selection PTP_1588_CLOCK_PCH
incidentally dropped the implicit dependency on the PCI. Restore it.

Fixes: 18d359ceb044 ("pch_gbe, ptp_pch: Fix the dependency direction between these drivers")
Reported-by: kernel test robot &lt;lkp@intel.com&gt;
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 55c8fca1dae1fb0d11deaa21b65a647dedb1bc50 ]

During the swap dependency on PCH_GBE to selection PTP_1588_CLOCK_PCH
incidentally dropped the implicit dependency on the PCI. Restore it.

Fixes: 18d359ceb044 ("pch_gbe, ptp_pch: Fix the dependency direction between these drivers")
Reported-by: kernel test robot &lt;lkp@intel.com&gt;
Signed-off-by: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp: improve max_adj check against unreasonable values</title>
<updated>2021-06-23T12:41:26+00:00</updated>
<author>
<name>Jakub Kicinski</name>
<email>kuba@kernel.org</email>
</author>
<published>2021-06-14T22:24:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3daa97817aa818ea783e6edcf4e9d9c47b6c330f'/>
<id>3daa97817aa818ea783e6edcf4e9d9c47b6c330f</id>
<content type='text'>
[ Upstream commit 475b92f932168a78da8109acd10bfb7578b8f2bb ]

Scaled PPM conversion to PPB may (on 64bit systems) result
in a value larger than s32 can hold (freq/scaled_ppm is a long).
This means the kernel will not correctly reject unreasonably
high -&gt;freq values (e.g. &gt; 4294967295ppb, 281474976645 scaled PPM).

The conversion is equivalent to a division by ~66 (65.536),
so the value of ppb is always smaller than ppm, but not small
enough to assume narrowing the type from long -&gt; s32 is okay.

Note that reasonable user space (e.g. ptp4l) will not use such
high values, anyway, 4289046510ppb ~= 4.3x, so the fix is
somewhat pedantic.

Fixes: d39a743511cd ("ptp: validate the requested frequency adjustment.")
Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 475b92f932168a78da8109acd10bfb7578b8f2bb ]

Scaled PPM conversion to PPB may (on 64bit systems) result
in a value larger than s32 can hold (freq/scaled_ppm is a long).
This means the kernel will not correctly reject unreasonably
high -&gt;freq values (e.g. &gt; 4294967295ppb, 281474976645 scaled PPM).

The conversion is equivalent to a division by ~66 (65.536),
so the value of ppb is always smaller than ppm, but not small
enough to assume narrowing the type from long -&gt; s32 is okay.

Note that reasonable user space (e.g. ptp4l) will not use such
high values, anyway, 4289046510ppb ~= 4.3x, so the fix is
somewhat pedantic.

Fixes: d39a743511cd ("ptp: validate the requested frequency adjustment.")
Fixes: d94ba80ebbea ("ptp: Added a brand new class driver for ptp clocks.")
Signed-off-by: Jakub Kicinski &lt;kuba@kernel.org&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp: free ptp device pin descriptors properly</title>
<updated>2020-01-23T07:22:51+00:00</updated>
<author>
<name>Vladis Dronov</name>
<email>vdronov@redhat.com</email>
</author>
<published>2020-01-13T13:00:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=4fd16cfcc3ae28cf42c67941fd529600f21bec39'/>
<id>4fd16cfcc3ae28cf42c67941fd529600f21bec39</id>
<content type='text'>
[ Upstream commit 75718584cb3c64e6269109d4d54f888ac5a5fd15 ]

There is a bug in ptp_clock_unregister(), where ptp_cleanup_pin_groups()
first frees ptp-&gt;pin_{,dev_}attr, but then posix_clock_unregister() needs
them to destroy a related sysfs device.

These functions can not be just swapped, as posix_clock_unregister() frees
ptp which is needed in the ptp_cleanup_pin_groups(). Fix this by calling
ptp_cleanup_pin_groups() in ptp_clock_release(), right before ptp is freed.

This makes this patch fix an UAF bug in a patch which fixes an UAF bug.

Reported-by: Antti Laakso &lt;antti.laakso@intel.com&gt;
Fixes: a33121e5487b ("ptp: fix the race between the release of ptp_clock and cdev")
Link: https://lore.kernel.org/netdev/3d2bd09735dbdaf003585ca376b7c1e5b69a19bd.camel@intel.com/
Signed-off-by: Vladis Dronov &lt;vdronov@redhat.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
[ Upstream commit 75718584cb3c64e6269109d4d54f888ac5a5fd15 ]

There is a bug in ptp_clock_unregister(), where ptp_cleanup_pin_groups()
first frees ptp-&gt;pin_{,dev_}attr, but then posix_clock_unregister() needs
them to destroy a related sysfs device.

These functions can not be just swapped, as posix_clock_unregister() frees
ptp which is needed in the ptp_cleanup_pin_groups(). Fix this by calling
ptp_cleanup_pin_groups() in ptp_clock_release(), right before ptp is freed.

This makes this patch fix an UAF bug in a patch which fixes an UAF bug.

Reported-by: Antti Laakso &lt;antti.laakso@intel.com&gt;
Fixes: a33121e5487b ("ptp: fix the race between the release of ptp_clock and cdev")
Link: https://lore.kernel.org/netdev/3d2bd09735dbdaf003585ca376b7c1e5b69a19bd.camel@intel.com/
Signed-off-by: Vladis Dronov &lt;vdronov@redhat.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>ptp: fix the race between the release of ptp_clock and cdev</title>
<updated>2020-01-04T18:18:48+00:00</updated>
<author>
<name>Vladis Dronov</name>
<email>vdronov@redhat.com</email>
</author>
<published>2019-12-27T02:26:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=bfa2e0cd3dfda64fde43c3dca3aeba298d2fe7ad'/>
<id>bfa2e0cd3dfda64fde43c3dca3aeba298d2fe7ad</id>
<content type='text'>
[ Upstream commit a33121e5487b424339636b25c35d3a180eaa5f5e ]

In a case when a ptp chardev (like /dev/ptp0) is open but an underlying
device is removed, closing this file leads to a race. This reproduces
easily in a kvm virtual machine:

ts# cat openptp0.c
int main() { ... fp = fopen("/dev/ptp0", "r"); ... sleep(10); }
ts# uname -r
5.5.0-rc3-46cf053e
ts# cat /proc/cmdline
... slub_debug=FZP
ts# modprobe ptp_kvm
ts# ./openptp0 &amp;
[1] 670
opened /dev/ptp0, sleeping 10s...
ts# rmmod ptp_kvm
ts# ls /dev/ptp*
ls: cannot access '/dev/ptp*': No such file or directory
ts# ...woken up
[   48.010809] general protection fault: 0000 [#1] SMP
[   48.012502] CPU: 6 PID: 658 Comm: openptp0 Not tainted 5.5.0-rc3-46cf053e #25
[   48.014624] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ...
[   48.016270] RIP: 0010:module_put.part.0+0x7/0x80
[   48.017939] RSP: 0018:ffffb3850073be00 EFLAGS: 00010202
[   48.018339] RAX: 000000006b6b6b6b RBX: 6b6b6b6b6b6b6b6b RCX: ffff89a476c00ad0
[   48.018936] RDX: fffff65a08d3ea08 RSI: 0000000000000247 RDI: 6b6b6b6b6b6b6b6b
[   48.019470] ...                                              ^^^ a slub poison
[   48.023854] Call Trace:
[   48.024050]  __fput+0x21f/0x240
[   48.024288]  task_work_run+0x79/0x90
[   48.024555]  do_exit+0x2af/0xab0
[   48.024799]  ? vfs_write+0x16a/0x190
[   48.025082]  do_group_exit+0x35/0x90
[   48.025387]  __x64_sys_exit_group+0xf/0x10
[   48.025737]  do_syscall_64+0x3d/0x130
[   48.026056]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   48.026479] RIP: 0033:0x7f53b12082f6
[   48.026792] ...
[   48.030945] Modules linked in: ptp i6300esb watchdog [last unloaded: ptp_kvm]
[   48.045001] Fixing recursive fault but reboot is needed!

This happens in:

static void __fput(struct file *file)
{   ...
    if (file-&gt;f_op-&gt;release)
        file-&gt;f_op-&gt;release(inode, file); &lt;&lt;&lt; cdev is kfree'd here
    if (unlikely(S_ISCHR(inode-&gt;i_mode) &amp;&amp; inode-&gt;i_cdev != NULL &amp;&amp;
             !(mode &amp; FMODE_PATH))) {
        cdev_put(inode-&gt;i_cdev); &lt;&lt;&lt; cdev fields are accessed here

Namely:

__fput()
  posix_clock_release()
    kref_put(&amp;clk-&gt;kref, delete_clock) &lt;&lt;&lt; the last reference
      delete_clock()
        delete_ptp_clock()
          kfree(ptp) &lt;&lt;&lt; cdev is embedded in ptp
  cdev_put
    module_put(p-&gt;owner) &lt;&lt;&lt; *p is kfree'd, bang!

Here cdev is embedded in posix_clock which is embedded in ptp_clock.
The race happens because ptp_clock's lifetime is controlled by two
refcounts: kref and cdev.kobj in posix_clock. This is wrong.

Make ptp_clock's sysfs device a parent of cdev with cdev_device_add()
created especially for such cases. This way the parent device with its
ptp_clock is not released until all references to the cdev are released.
This adds a requirement that an initialized but not exposed struct
device should be provided to posix_clock_register() by a caller instead
of a simple dev_t.

This approach was adopted from the commit 72139dfa2464 ("watchdog: Fix
the race between the release of watchdog_core_data and cdev"). See
details of the implementation in the commit 233ed09d7fda ("chardev: add
helper function to register char devs with a struct device").

Link: https://lore.kernel.org/linux-fsdevel/20191125125342.6189-1-vdronov@redhat.com/T/#u
Analyzed-by: Stephen Johnston &lt;sjohnsto@redhat.com&gt;
Analyzed-by: Vern Lovejoy &lt;vlovejoy@redhat.com&gt;
Signed-off-by: Vladis Dronov &lt;vdronov@redhat.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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<pre>
[ Upstream commit a33121e5487b424339636b25c35d3a180eaa5f5e ]

In a case when a ptp chardev (like /dev/ptp0) is open but an underlying
device is removed, closing this file leads to a race. This reproduces
easily in a kvm virtual machine:

ts# cat openptp0.c
int main() { ... fp = fopen("/dev/ptp0", "r"); ... sleep(10); }
ts# uname -r
5.5.0-rc3-46cf053e
ts# cat /proc/cmdline
... slub_debug=FZP
ts# modprobe ptp_kvm
ts# ./openptp0 &amp;
[1] 670
opened /dev/ptp0, sleeping 10s...
ts# rmmod ptp_kvm
ts# ls /dev/ptp*
ls: cannot access '/dev/ptp*': No such file or directory
ts# ...woken up
[   48.010809] general protection fault: 0000 [#1] SMP
[   48.012502] CPU: 6 PID: 658 Comm: openptp0 Not tainted 5.5.0-rc3-46cf053e #25
[   48.014624] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), ...
[   48.016270] RIP: 0010:module_put.part.0+0x7/0x80
[   48.017939] RSP: 0018:ffffb3850073be00 EFLAGS: 00010202
[   48.018339] RAX: 000000006b6b6b6b RBX: 6b6b6b6b6b6b6b6b RCX: ffff89a476c00ad0
[   48.018936] RDX: fffff65a08d3ea08 RSI: 0000000000000247 RDI: 6b6b6b6b6b6b6b6b
[   48.019470] ...                                              ^^^ a slub poison
[   48.023854] Call Trace:
[   48.024050]  __fput+0x21f/0x240
[   48.024288]  task_work_run+0x79/0x90
[   48.024555]  do_exit+0x2af/0xab0
[   48.024799]  ? vfs_write+0x16a/0x190
[   48.025082]  do_group_exit+0x35/0x90
[   48.025387]  __x64_sys_exit_group+0xf/0x10
[   48.025737]  do_syscall_64+0x3d/0x130
[   48.026056]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[   48.026479] RIP: 0033:0x7f53b12082f6
[   48.026792] ...
[   48.030945] Modules linked in: ptp i6300esb watchdog [last unloaded: ptp_kvm]
[   48.045001] Fixing recursive fault but reboot is needed!

This happens in:

static void __fput(struct file *file)
{   ...
    if (file-&gt;f_op-&gt;release)
        file-&gt;f_op-&gt;release(inode, file); &lt;&lt;&lt; cdev is kfree'd here
    if (unlikely(S_ISCHR(inode-&gt;i_mode) &amp;&amp; inode-&gt;i_cdev != NULL &amp;&amp;
             !(mode &amp; FMODE_PATH))) {
        cdev_put(inode-&gt;i_cdev); &lt;&lt;&lt; cdev fields are accessed here

Namely:

__fput()
  posix_clock_release()
    kref_put(&amp;clk-&gt;kref, delete_clock) &lt;&lt;&lt; the last reference
      delete_clock()
        delete_ptp_clock()
          kfree(ptp) &lt;&lt;&lt; cdev is embedded in ptp
  cdev_put
    module_put(p-&gt;owner) &lt;&lt;&lt; *p is kfree'd, bang!

Here cdev is embedded in posix_clock which is embedded in ptp_clock.
The race happens because ptp_clock's lifetime is controlled by two
refcounts: kref and cdev.kobj in posix_clock. This is wrong.

Make ptp_clock's sysfs device a parent of cdev with cdev_device_add()
created especially for such cases. This way the parent device with its
ptp_clock is not released until all references to the cdev are released.
This adds a requirement that an initialized but not exposed struct
device should be provided to posix_clock_register() by a caller instead
of a simple dev_t.

This approach was adopted from the commit 72139dfa2464 ("watchdog: Fix
the race between the release of watchdog_core_data and cdev"). See
details of the implementation in the commit 233ed09d7fda ("chardev: add
helper function to register char devs with a struct device").

Link: https://lore.kernel.org/linux-fsdevel/20191125125342.6189-1-vdronov@redhat.com/T/#u
Analyzed-by: Stephen Johnston &lt;sjohnsto@redhat.com&gt;
Analyzed-by: Vern Lovejoy &lt;vlovejoy@redhat.com&gt;
Signed-off-by: Vladis Dronov &lt;vdronov@redhat.com&gt;
Acked-by: Richard Cochran &lt;richardcochran@gmail.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
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