<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git, branch v6.4.1</title>
<subtitle>Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git</subtitle>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/'/>
<entry>
<title>Linux 6.4.1</title>
<updated>2023-07-01T11:12:42+00:00</updated>
<author>
<name>Greg Kroah-Hartman</name>
<email>gregkh@linuxfoundation.org</email>
</author>
<published>2023-07-01T11:12:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=59377679473491963a599bfd51cc9877492312ee'/>
<id>59377679473491963a599bfd51cc9877492312ee</id>
<content type='text'>
Link: https://lore.kernel.org/r/20230629184151.888604958@linuxfoundation.org
Tested-by: Ronald Warsow &lt;rwarsow@gmx.de&gt;
Link: https://lore.kernel.org/r/20230630055626.202608973@linuxfoundation.org
Link: https://lore.kernel.org/r/20230630072101.040486316@linuxfoundation.org
Tested-by: Ron Economos &lt;re@w6rz.net&gt;
Tested-by: Jon Hunter &lt;jonathanh@nvidia.com&gt;
Tested-by: Ronald Warsow &lt;rwarsow@gmx.de&gt;
Tested-by: Rudi Heitbaum &lt;rudi@heitbaum.com&gt;
Tested-by: Linux Kernel Functional Testing &lt;lkft@linaro.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>
Link: https://lore.kernel.org/r/20230629184151.888604958@linuxfoundation.org
Tested-by: Ronald Warsow &lt;rwarsow@gmx.de&gt;
Link: https://lore.kernel.org/r/20230630055626.202608973@linuxfoundation.org
Link: https://lore.kernel.org/r/20230630072101.040486316@linuxfoundation.org
Tested-by: Ron Economos &lt;re@w6rz.net&gt;
Tested-by: Jon Hunter &lt;jonathanh@nvidia.com&gt;
Tested-by: Ronald Warsow &lt;rwarsow@gmx.de&gt;
Tested-by: Rudi Heitbaum &lt;rudi@heitbaum.com&gt;
Tested-by: Linux Kernel Functional Testing &lt;lkft@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>xtensa: fix NOMMU build with lock_mm_and_find_vma() conversion</title>
<updated>2023-07-01T11:12:42+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-07-01T01:24:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=2aad4f30f4e4702fc3cfff67bc1ed5aa85510aec'/>
<id>2aad4f30f4e4702fc3cfff67bc1ed5aa85510aec</id>
<content type='text'>
commit d85a143b69abb4d7544227e26d12c4c7735ab27d upstream.

It turns out that xtensa has a really odd configuration situation: you
can do a no-MMU config, but still have the page fault code enabled.
Which doesn't sound all that sensible, but it turns out that xtensa can
have protection faults even without the MMU, and we have this:

    config PFAULT
        bool "Handle protection faults" if EXPERT &amp;&amp; !MMU
        default y
        help
          Handle protection faults. MMU configurations must enable it.
          noMMU configurations may disable it if used memory map never
          generates protection faults or faults are always fatal.

          If unsure, say Y.

which completely violated my expectations of the page fault handling.

End result: Guenter reports that the xtensa no-MMU builds all fail with

  arch/xtensa/mm/fault.c: In function ‘do_page_fault’:
  arch/xtensa/mm/fault.c:133:8: error: implicit declaration of function ‘lock_mm_and_find_vma’

because I never exposed the new lock_mm_and_find_vma() function for the
no-MMU case.

Doing so is simple enough, and fixes the problem.

Reported-and-tested-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Fixes: a050ba1e7422 ("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()")
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.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 d85a143b69abb4d7544227e26d12c4c7735ab27d upstream.

It turns out that xtensa has a really odd configuration situation: you
can do a no-MMU config, but still have the page fault code enabled.
Which doesn't sound all that sensible, but it turns out that xtensa can
have protection faults even without the MMU, and we have this:

    config PFAULT
        bool "Handle protection faults" if EXPERT &amp;&amp; !MMU
        default y
        help
          Handle protection faults. MMU configurations must enable it.
          noMMU configurations may disable it if used memory map never
          generates protection faults or faults are always fatal.

          If unsure, say Y.

which completely violated my expectations of the page fault handling.

End result: Guenter reports that the xtensa no-MMU builds all fail with

  arch/xtensa/mm/fault.c: In function ‘do_page_fault’:
  arch/xtensa/mm/fault.c:133:8: error: implicit declaration of function ‘lock_mm_and_find_vma’

because I never exposed the new lock_mm_and_find_vma() function for the
no-MMU case.

Doing so is simple enough, and fixes the problem.

Reported-and-tested-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Fixes: a050ba1e7422 ("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()")
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>csky: fix up lock_mm_and_find_vma() conversion</title>
<updated>2023-07-01T11:12:41+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-06-30T06:34:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=87d780e048bda5cda800f8ffc5199ecdd53b1412'/>
<id>87d780e048bda5cda800f8ffc5199ecdd53b1412</id>
<content type='text'>
commit e55e5df193d247a38a5e1ac65a5316a0adcc22fa upstream.

As already mentioned in my merge message for the 'expand-stack' branch,
we have something like 24 different versions of the page fault path for
all our different architectures, all just _slightly_ different due to
various historical reasons (usually related to exactly when they
branched off the original i386 version, and the details of the other
architectures they had in their history).

And a few of them had some silly mistake in the conversion.

Most of the architectures call the faulting address 'address' in the
fault path.  But not all.  Some just call it 'addr'.  And if you end up
doing a bit too much copy-and-paste, you end up with the wrong version
in the places that do it differently.

In this case it was csky.

Fixes: a050ba1e7422 ("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()")
Reported-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.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 e55e5df193d247a38a5e1ac65a5316a0adcc22fa upstream.

As already mentioned in my merge message for the 'expand-stack' branch,
we have something like 24 different versions of the page fault path for
all our different architectures, all just _slightly_ different due to
various historical reasons (usually related to exactly when they
branched off the original i386 version, and the details of the other
architectures they had in their history).

And a few of them had some silly mistake in the conversion.

Most of the architectures call the faulting address 'address' in the
fault path.  But not all.  Some just call it 'addr'.  And if you end up
doing a bit too much copy-and-paste, you end up with the wrong version
in the places that do it differently.

In this case it was csky.

Fixes: a050ba1e7422 ("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()")
Reported-by: Guenter Roeck &lt;linux@roeck-us.net&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>parisc: fix expand_stack() conversion</title>
<updated>2023-07-01T11:12:41+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-06-30T06:04:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=0d98e5325f1f423be19c6124905133951cc17198'/>
<id>0d98e5325f1f423be19c6124905133951cc17198</id>
<content type='text'>
commit ea3f8272876f2958463992f6736ab690fde7fa9c upstream.

In commit 8d7071af8907 ("mm: always expand the stack with the mmap write
lock held") I tried to deal with the remaining odd page fault handling
cases.  The oddest one is ia64, which has stacks that grow both up and
down.  And because ia64 was _so_ odd, I asked people to verify the end
result.

But a close second oddity is parisc, which is the only one that has a
main stack growing up (our "CONFIG_STACK_GROWSUP" config option).  But
it looked obvious enough that I didn't worry about it.

I should have worried a bit more.  Not because it was particularly
complex, but because I just used the wrong variable name.

The previous vma isn't called "prev", it's called "prev_vma".  Blush.

Fixes: 8d7071af8907 ("mm: always expand the stack with the mmap write lock held")
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.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 ea3f8272876f2958463992f6736ab690fde7fa9c upstream.

In commit 8d7071af8907 ("mm: always expand the stack with the mmap write
lock held") I tried to deal with the remaining odd page fault handling
cases.  The oddest one is ia64, which has stacks that grow both up and
down.  And because ia64 was _so_ odd, I asked people to verify the end
result.

But a close second oddity is parisc, which is the only one that has a
main stack growing up (our "CONFIG_STACK_GROWSUP" config option).  But
it looked obvious enough that I didn't worry about it.

I should have worried a bit more.  Not because it was particularly
complex, but because I just used the wrong variable name.

The previous vma isn't called "prev", it's called "prev_vma".  Blush.

Fixes: 8d7071af8907 ("mm: always expand the stack with the mmap write lock held")
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>sparc32: fix lock_mm_and_find_vma() conversion</title>
<updated>2023-07-01T11:12:41+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-06-30T03:41:24+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=23d1e960cd12b38000908839c6b2ff494223149e'/>
<id>23d1e960cd12b38000908839c6b2ff494223149e</id>
<content type='text'>
commit 0b26eadbf200abf6c97c6d870286c73219cdac65 upstream.

The sparc32 conversion to lock_mm_and_find_vma() in commit a050ba1e7422
("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()")
missed the fact that we didn't actually have a 'regs' pointer available
in the 'force_user_fault()' case.

It's there in the regular page fault path ("do_sparc_fault()"), but not
the window underflow/overflow paths.

Which is all fine - we can just pass in a NULL pointer.  The register
state is only used to avoid deadlock with kernel faults, which is not
the case for any of these register window faults.

Reported-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Fixes: a050ba1e7422 ("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()")
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Naresh Kamboju &lt;naresh.kamboju@linaro.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 0b26eadbf200abf6c97c6d870286c73219cdac65 upstream.

The sparc32 conversion to lock_mm_and_find_vma() in commit a050ba1e7422
("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()")
missed the fact that we didn't actually have a 'regs' pointer available
in the 'force_user_fault()' case.

It's there in the regular page fault path ("do_sparc_fault()"), but not
the window underflow/overflow paths.

Which is all fine - we can just pass in a NULL pointer.  The register
state is only used to avoid deadlock with kernel faults, which is not
the case for any of these register window faults.

Reported-by: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Fixes: a050ba1e7422 ("mm/fault: convert remaining simple cases to lock_mm_and_find_vma()")
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Cc: Naresh Kamboju &lt;naresh.kamboju@linaro.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Revert "thermal/drivers/mediatek: Use devm_of_iomap to avoid resource leak in mtk_thermal_probe"</title>
<updated>2023-07-01T11:12:41+00:00</updated>
<author>
<name>Ricardo Cañuelo</name>
<email>ricardo.canuelo@collabora.com</email>
</author>
<published>2023-05-25T12:18:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=7a11f6e08edf13234cac84ff16f13f8204bc9374'/>
<id>7a11f6e08edf13234cac84ff16f13f8204bc9374</id>
<content type='text'>
commit 86edac7d3888c715fe3a81bd61f3617ecfe2e1dd upstream.

This reverts commit f05c7b7d9ea9477fcc388476c6f4ade8c66d2d26.

That change was causing a regression in the generic-adc-thermal-probed
bootrr test as reported in the kernelci-results list [1].
A proper rework will take longer, so revert it for now.

[1] https://groups.io/g/kernelci-results/message/42660

Fixes: f05c7b7d9ea9 ("thermal/drivers/mediatek: Use devm_of_iomap to avoid resource leak in mtk_thermal_probe")
Signed-off-by: Ricardo Cañuelo &lt;ricardo.canuelo@collabora.com&gt;
Suggested-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Reviewed-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Link: https://lore.kernel.org/r/20230525121811.3360268-1-ricardo.canuelo@collabora.com
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 86edac7d3888c715fe3a81bd61f3617ecfe2e1dd upstream.

This reverts commit f05c7b7d9ea9477fcc388476c6f4ade8c66d2d26.

That change was causing a regression in the generic-adc-thermal-probed
bootrr test as reported in the kernelci-results list [1].
A proper rework will take longer, so revert it for now.

[1] https://groups.io/g/kernelci-results/message/42660

Fixes: f05c7b7d9ea9 ("thermal/drivers/mediatek: Use devm_of_iomap to avoid resource leak in mtk_thermal_probe")
Signed-off-by: Ricardo Cañuelo &lt;ricardo.canuelo@collabora.com&gt;
Suggested-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Reviewed-by: AngeloGioacchino Del Regno &lt;angelogioacchino.delregno@collabora.com&gt;
Signed-off-by: Daniel Lezcano &lt;daniel.lezcano@linaro.org&gt;
Link: https://lore.kernel.org/r/20230525121811.3360268-1-ricardo.canuelo@collabora.com
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>HID: logitech-hidpp: add HIDPP_QUIRK_DELAYED_INIT for the T651.</title>
<updated>2023-07-01T11:12:41+00:00</updated>
<author>
<name>Mike Hommey</name>
<email>mh@glandium.org</email>
</author>
<published>2023-06-17T23:09:57+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=e6d864166aaf6e4040a3614640262cb796153544'/>
<id>e6d864166aaf6e4040a3614640262cb796153544</id>
<content type='text'>
commit 5fe251112646d8626818ea90f7af325bab243efa upstream.

commit 498ba2069035 ("HID: logitech-hidpp: Don't restart communication if
not necessary") put restarting communication behind that flag, and this
was apparently necessary on the T651, but the flag was not set for it.

Fixes: 498ba2069035 ("HID: logitech-hidpp: Don't restart communication if not necessary")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Hommey &lt;mh@glandium.org&gt;
Link: https://lore.kernel.org/r/20230617230957.6mx73th4blv7owqk@glandium.org
Signed-off-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&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 5fe251112646d8626818ea90f7af325bab243efa upstream.

commit 498ba2069035 ("HID: logitech-hidpp: Don't restart communication if
not necessary") put restarting communication behind that flag, and this
was apparently necessary on the T651, but the flag was not set for it.

Fixes: 498ba2069035 ("HID: logitech-hidpp: Don't restart communication if not necessary")
Cc: stable@vger.kernel.org
Signed-off-by: Mike Hommey &lt;mh@glandium.org&gt;
Link: https://lore.kernel.org/r/20230617230957.6mx73th4blv7owqk@glandium.org
Signed-off-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>HID: hidraw: fix data race on device refcount</title>
<updated>2023-07-01T11:12:41+00:00</updated>
<author>
<name>Ludvig Michaelsson</name>
<email>ludvig.michaelsson@yubico.com</email>
</author>
<published>2023-06-21T11:17:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=05b47034e2488c2924e5c032e20a1979d012b5b5'/>
<id>05b47034e2488c2924e5c032e20a1979d012b5b5</id>
<content type='text'>
commit 944ee77dc6ec7b0afd8ec70ffc418b238c92f12b upstream.

The hidraw_open() function increments the hidraw device reference
counter. The counter has no dedicated synchronization mechanism,
resulting in a potential data race when concurrently opening a device.

The race is a regression introduced by commit 8590222e4b02 ("HID:
hidraw: Replace hidraw device table mutex with a rwsem"). While
minors_rwsem is intended to protect the hidraw_table itself, by instead
acquiring the lock for writing, the reference counter is also protected.
This is symmetrical to hidraw_release().

Link: https://github.com/systemd/systemd/issues/27947
Fixes: 8590222e4b02 ("HID: hidraw: Replace hidraw device table mutex with a rwsem")
Cc: stable@vger.kernel.org
Signed-off-by: Ludvig Michaelsson &lt;ludvig.michaelsson@yubico.com&gt;
Link: https://lore.kernel.org/r/20230621-hidraw-race-v1-1-a58e6ac69bab@yubico.com
Signed-off-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&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 944ee77dc6ec7b0afd8ec70ffc418b238c92f12b upstream.

The hidraw_open() function increments the hidraw device reference
counter. The counter has no dedicated synchronization mechanism,
resulting in a potential data race when concurrently opening a device.

The race is a regression introduced by commit 8590222e4b02 ("HID:
hidraw: Replace hidraw device table mutex with a rwsem"). While
minors_rwsem is intended to protect the hidraw_table itself, by instead
acquiring the lock for writing, the reference counter is also protected.
This is symmetrical to hidraw_release().

Link: https://github.com/systemd/systemd/issues/27947
Fixes: 8590222e4b02 ("HID: hidraw: Replace hidraw device table mutex with a rwsem")
Cc: stable@vger.kernel.org
Signed-off-by: Ludvig Michaelsson &lt;ludvig.michaelsson@yubico.com&gt;
Link: https://lore.kernel.org/r/20230621-hidraw-race-v1-1-a58e6ac69bab@yubico.com
Signed-off-by: Benjamin Tissoires &lt;benjamin.tissoires@redhat.com&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fbdev: fix potential OOB read in fast_imageblit()</title>
<updated>2023-07-01T11:12:41+00:00</updated>
<author>
<name>Zhang Shurong</name>
<email>zhang_shurong@foxmail.com</email>
</author>
<published>2023-06-24T16:16:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=14fdcf965dc569f2c879fc2d234d95bc2711d6c2'/>
<id>14fdcf965dc569f2c879fc2d234d95bc2711d6c2</id>
<content type='text'>
commit c2d22806aecb24e2de55c30a06e5d6eb297d161d upstream.

There is a potential OOB read at fast_imageblit, for
"colortab[(*src &gt;&gt; 4)]" can become a negative value due to
"const char *s = image-&gt;data, *src".
This change makes sure the index for colortab always positive
or zero.

Similar commit:
https://patchwork.kernel.org/patch/11746067

Potential bug report:
https://groups.google.com/g/syzkaller-bugs/c/9ubBXKeKXf4/m/k-QXy4UgAAAJ

Signed-off-by: Zhang Shurong &lt;zhang_shurong@foxmail.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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commit c2d22806aecb24e2de55c30a06e5d6eb297d161d upstream.

There is a potential OOB read at fast_imageblit, for
"colortab[(*src &gt;&gt; 4)]" can become a negative value due to
"const char *s = image-&gt;data, *src".
This change makes sure the index for colortab always positive
or zero.

Similar commit:
https://patchwork.kernel.org/patch/11746067

Potential bug report:
https://groups.google.com/g/syzkaller-bugs/c/9ubBXKeKXf4/m/k-QXy4UgAAAJ

Signed-off-by: Zhang Shurong &lt;zhang_shurong@foxmail.com&gt;
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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<entry>
<title>mm/khugepaged: fix regression in collapse_file()</title>
<updated>2023-07-01T11:12:40+00:00</updated>
<author>
<name>Hugh Dickins</name>
<email>hughd@google.com</email>
</author>
<published>2023-06-29T04:31:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=00d5932e09d74ba442aee1f93db59a2d53bb5afd'/>
<id>00d5932e09d74ba442aee1f93db59a2d53bb5afd</id>
<content type='text'>
commit e8c716bc6812202ccf4ce0f0bad3428b794fb39c upstream.

There is no xas_pause(&amp;xas) in collapse_file()'s main loop, at the points
where it does xas_unlock_irq(&amp;xas) and then continues.

That would explain why, once two weeks ago and twice yesterday, I have
hit the VM_BUG_ON_PAGE(page != xas_load(&amp;xas), page) since "mm/khugepaged:
fix iteration in collapse_file" removed the xas_set(&amp;xas, index) just
before it: xas.xa_node could be left pointing to a stale node, if there
was concurrent activity on the file which transformed its xarray.

I tried inserting xas_pause()s, but then even bootup crashed on that
VM_BUG_ON_PAGE(): there appears to be a subtle "nextness" implicit in
xas_pause().

xas_next() and xas_pause() are good for use in simple loops, but not in
this one: xas_set() worked well until now, so use xas_set(&amp;xas, index)
explicitly at the head of the loop; and change that VM_BUG_ON_PAGE() not
to need its own xas_set(), and not to interfere with the xa_state (which
would probably stop the crashes from xas_pause(), but I trust that less).

The user-visible effects of this bug (if VM_BUG_ONs are configured out)
would be data loss and data leak - potentially - though in practice I
expect it is more likely that a subsequent check (e.g. on mapping or on
nr_none) would notice an inconsistency, and just abandon the collapse.

Link: https://lore.kernel.org/linux-mm/f18e4b64-3f88-a8ab-56cc-d1f5f9c58d4@google.com/
Fixes: c8a8f3b4a95a ("mm/khugepaged: fix iteration in collapse_file")
Signed-off-by: Hugh Dickins &lt;hughd@google.com&gt;
Cc: stable@kernel.org
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: David Stevens &lt;stevensd@chromium.org&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
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<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit e8c716bc6812202ccf4ce0f0bad3428b794fb39c upstream.

There is no xas_pause(&amp;xas) in collapse_file()'s main loop, at the points
where it does xas_unlock_irq(&amp;xas) and then continues.

That would explain why, once two weeks ago and twice yesterday, I have
hit the VM_BUG_ON_PAGE(page != xas_load(&amp;xas), page) since "mm/khugepaged:
fix iteration in collapse_file" removed the xas_set(&amp;xas, index) just
before it: xas.xa_node could be left pointing to a stale node, if there
was concurrent activity on the file which transformed its xarray.

I tried inserting xas_pause()s, but then even bootup crashed on that
VM_BUG_ON_PAGE(): there appears to be a subtle "nextness" implicit in
xas_pause().

xas_next() and xas_pause() are good for use in simple loops, but not in
this one: xas_set() worked well until now, so use xas_set(&amp;xas, index)
explicitly at the head of the loop; and change that VM_BUG_ON_PAGE() not
to need its own xas_set(), and not to interfere with the xa_state (which
would probably stop the crashes from xas_pause(), but I trust that less).

The user-visible effects of this bug (if VM_BUG_ONs are configured out)
would be data loss and data leak - potentially - though in practice I
expect it is more likely that a subsequent check (e.g. on mapping or on
nr_none) would notice an inconsistency, and just abandon the collapse.

Link: https://lore.kernel.org/linux-mm/f18e4b64-3f88-a8ab-56cc-d1f5f9c58d4@google.com/
Fixes: c8a8f3b4a95a ("mm/khugepaged: fix iteration in collapse_file")
Signed-off-by: Hugh Dickins &lt;hughd@google.com&gt;
Cc: stable@kernel.org
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: David Stevens &lt;stevensd@chromium.org&gt;
Cc: Peter Xu &lt;peterx@redhat.com&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
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</content>
</entry>
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