<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/x86, branch v6.0</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>Merge tag 'perf-urgent-2022-10-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2022-10-02T16:41:27+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-10-02T16:41:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=febae48afe6063105a0fad83d8e12a6addda7c6a'/>
<id>febae48afe6063105a0fad83d8e12a6addda7c6a</id>
<content type='text'>
Pull misc perf fixes from Ingo Molnar:

 - Fix a PMU enumeration/initialization bug on Intel Alder Lake CPUs

 - Fix KVM guest PEBS register handling

 - Fix race/reentry bug in perf_output_read_group() reading of PMU
   counters

* tag 'perf-urgent-2022-10-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Fix reentry problem in perf_output_read_group()
  perf/x86/core: Completely disable guest PEBS via guest's global_ctrl
  perf/x86/intel: Fix unchecked MSR access error for Alder Lake N
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull misc perf fixes from Ingo Molnar:

 - Fix a PMU enumeration/initialization bug on Intel Alder Lake CPUs

 - Fix KVM guest PEBS register handling

 - Fix race/reentry bug in perf_output_read_group() reading of PMU
   counters

* tag 'perf-urgent-2022-10-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf/core: Fix reentry problem in perf_output_read_group()
  perf/x86/core: Completely disable guest PEBS via guest's global_ctrl
  perf/x86/intel: Fix unchecked MSR access error for Alder Lake N
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'x86_urgent_for_v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2022-10-02T16:30:35+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-10-02T16:30:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=534b0abc627a4034ecaf177e780b1680e61b37f4'/>
<id>534b0abc627a4034ecaf177e780b1680e61b37f4</id>
<content type='text'>
Pull x86 fixes from Borislav Petkov:

 - Add the respective UP last level cache mask accessors in order not to
   cause segfaults when lscpu accesses their representation in sysfs

 - Fix for a race in the alternatives batch patching machinery when
   kprobes are set

* tag 'x86_urgent_for_v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cacheinfo: Add a cpu_llc_shared_mask() UP variant
  x86/alternative: Fix race in try_get_desc()
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull x86 fixes from Borislav Petkov:

 - Add the respective UP last level cache mask accessors in order not to
   cause segfaults when lscpu accesses their representation in sysfs

 - Fix for a race in the alternatives batch patching machinery when
   kprobes are set

* tag 'x86_urgent_for_v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cacheinfo: Add a cpu_llc_shared_mask() UP variant
  x86/alternative: Fix race in try_get_desc()
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'for-linus-6.0' of git://git.kernel.org/pub/scm/virt/kvm/kvm</title>
<updated>2022-09-30T22:49:13+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-09-30T22:49:13+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=920541bb0b9bf08d1455890694fbb2bbffb7a12b'/>
<id>920541bb0b9bf08d1455890694fbb2bbffb7a12b</id>
<content type='text'>
Pull kvm fixes from Paolo Bonzini:
 "A small fix to the reported set of supported CPUID bits, and selftests
  fixes:

   - Skip tests that require EPT when it is not available

   - Do not hang when a test fails with an empty stack trace

   - avoid spurious failure when running access_tracking_perf_test in a
     KVM guest

   - work around GCC's tendency to optimize loops into mem*() functions,
     which breaks because the guest code in selftests cannot call into
     PLTs

   - fix -Warray-bounds error in fix_hypercall_test"

* tag 'for-linus-6.0' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: selftests: Compare insn opcodes directly in fix_hypercall_test
  KVM: selftests: Implement memcmp(), memcpy(), and memset() for guest use
  KVM: x86: Hide IA32_PLATFORM_DCA_CAP[31:0] from the guest
  KVM: selftests: Gracefully handle empty stack traces
  KVM: selftests: replace assertion with warning in access_tracking_perf_test
  KVM: selftests: Skip tests that require EPT when it is not available
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull kvm fixes from Paolo Bonzini:
 "A small fix to the reported set of supported CPUID bits, and selftests
  fixes:

   - Skip tests that require EPT when it is not available

   - Do not hang when a test fails with an empty stack trace

   - avoid spurious failure when running access_tracking_perf_test in a
     KVM guest

   - work around GCC's tendency to optimize loops into mem*() functions,
     which breaks because the guest code in selftests cannot call into
     PLTs

   - fix -Warray-bounds error in fix_hypercall_test"

* tag 'for-linus-6.0' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: selftests: Compare insn opcodes directly in fix_hypercall_test
  KVM: selftests: Implement memcmp(), memcpy(), and memset() for guest use
  KVM: x86: Hide IA32_PLATFORM_DCA_CAP[31:0] from the guest
  KVM: selftests: Gracefully handle empty stack traces
  KVM: selftests: replace assertion with warning in access_tracking_perf_test
  KVM: selftests: Skip tests that require EPT when it is not available
</pre>
</div>
</content>
</entry>
<entry>
<title>KVM: x86: Hide IA32_PLATFORM_DCA_CAP[31:0] from the guest</title>
<updated>2022-09-30T10:38:01+00:00</updated>
<author>
<name>Jim Mattson</name>
<email>jmattson@google.com</email>
</author>
<published>2022-09-22T23:18:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=aae2e72229cdb21f90df2dbe4244c977e5d3265b'/>
<id>aae2e72229cdb21f90df2dbe4244c977e5d3265b</id>
<content type='text'>
The only thing reported by CPUID.9 is the value of
IA32_PLATFORM_DCA_CAP[31:0] in EAX. This MSR doesn't even exist in the
guest, since CPUID.1:ECX.DCA[bit 18] is clear in the guest.

Clear CPUID.9 in KVM_GET_SUPPORTED_CPUID.

Fixes: 24c82e576b78 ("KVM: Sanitize cpuid")
Signed-off-by: Jim Mattson &lt;jmattson@google.com&gt;
Message-Id: &lt;20220922231854.249383-1-jmattson@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The only thing reported by CPUID.9 is the value of
IA32_PLATFORM_DCA_CAP[31:0] in EAX. This MSR doesn't even exist in the
guest, since CPUID.1:ECX.DCA[bit 18] is clear in the guest.

Clear CPUID.9 in KVM_GET_SUPPORTED_CPUID.

Fixes: 24c82e576b78 ("KVM: Sanitize cpuid")
Signed-off-by: Jim Mattson &lt;jmattson@google.com&gt;
Message-Id: &lt;20220922231854.249383-1-jmattson@google.com&gt;
Signed-off-by: Paolo Bonzini &lt;pbonzini@redhat.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/cacheinfo: Add a cpu_llc_shared_mask() UP variant</title>
<updated>2022-09-28T16:35:37+00:00</updated>
<author>
<name>Borislav Petkov</name>
<email>bp@suse.de</email>
</author>
<published>2022-08-19T17:47:44+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=df5b035b5683d6a25f077af889fb88e09827f8bc'/>
<id>df5b035b5683d6a25f077af889fb88e09827f8bc</id>
<content type='text'>
On a CONFIG_SMP=n kernel, the LLC shared mask is 0, which prevents
__cache_amd_cpumap_setup() from doing the L3 masks setup, and more
specifically from setting up the shared_cpu_map and shared_cpu_list
files in sysfs, leading to lscpu from util-linux getting confused and
segfaulting.

Add a cpu_llc_shared_mask() UP variant which returns a mask with a
single bit set, i.e., for CPU0.

Fixes: 2b83809a5e6d ("x86/cpu/amd: Derive L3 shared_cpu_map from cpu_llc_shared_mask")
Reported-by: Saurabh Sengar &lt;ssengar@linux.microsoft.com&gt;
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Link: https://lore.kernel.org/r/1660148115-302-1-git-send-email-ssengar@linux.microsoft.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
On a CONFIG_SMP=n kernel, the LLC shared mask is 0, which prevents
__cache_amd_cpumap_setup() from doing the L3 masks setup, and more
specifically from setting up the shared_cpu_map and shared_cpu_list
files in sysfs, leading to lscpu from util-linux getting confused and
segfaulting.

Add a cpu_llc_shared_mask() UP variant which returns a mask with a
single bit set, i.e., for CPU0.

Fixes: 2b83809a5e6d ("x86/cpu/amd: Derive L3 shared_cpu_map from cpu_llc_shared_mask")
Reported-by: Saurabh Sengar &lt;ssengar@linux.microsoft.com&gt;
Signed-off-by: Borislav Petkov &lt;bp@suse.de&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Link: https://lore.kernel.org/r/1660148115-302-1-git-send-email-ssengar@linux.microsoft.com
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/alternative: Fix race in try_get_desc()</title>
<updated>2022-09-27T20:50:26+00:00</updated>
<author>
<name>Nadav Amit</name>
<email>namit@vmware.com</email>
</author>
<published>2022-09-21T18:09:32+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=efd608fa7403ba106412b437f873929e2c862e28'/>
<id>efd608fa7403ba106412b437f873929e2c862e28</id>
<content type='text'>
I encountered some occasional crashes of poke_int3_handler() when
kprobes are set, while accessing desc-&gt;vec.

The text poke mechanism claims to have an RCU-like behavior, but it
does not appear that there is any quiescent state to ensure that
nobody holds reference to desc. As a result, the following race
appears to be possible, which can lead to memory corruption.

  CPU0					CPU1
  ----					----
  text_poke_bp_batch()
  -&gt; smp_store_release(&amp;bp_desc, &amp;desc)

  [ notice that desc is on
    the stack			]

					poke_int3_handler()

					[ int3 might be kprobe's
					  so sync events are do not
					  help ]

					-&gt; try_get_desc(descp=&amp;bp_desc)
					   desc = __READ_ONCE(bp_desc)

					   if (!desc) [false, success]
  WRITE_ONCE(bp_desc, NULL);
  atomic_dec_and_test(&amp;desc.refs)

  [ success, desc space on the stack
    is being reused and might have
    non-zero value. ]
					arch_atomic_inc_not_zero(&amp;desc-&gt;refs)

					[ might succeed since desc points to
					  stack memory that was freed and might
					  be reused. ]

Fix this issue with small backportable patch. Instead of trying to
make RCU-like behavior for bp_desc, just eliminate the unnecessary
level of indirection of bp_desc, and hold the whole descriptor as a
global.  Anyhow, there is only a single descriptor at any given
moment.

Fixes: 1f676247f36a4 ("x86/alternatives: Implement a better poke_int3_handler() completion scheme")
Signed-off-by: Nadav Amit &lt;namit@vmware.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: stable@kernel.org
Link: https://lkml.kernel.org/r/20220920224743.3089-1-namit@vmware.com
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
I encountered some occasional crashes of poke_int3_handler() when
kprobes are set, while accessing desc-&gt;vec.

The text poke mechanism claims to have an RCU-like behavior, but it
does not appear that there is any quiescent state to ensure that
nobody holds reference to desc. As a result, the following race
appears to be possible, which can lead to memory corruption.

  CPU0					CPU1
  ----					----
  text_poke_bp_batch()
  -&gt; smp_store_release(&amp;bp_desc, &amp;desc)

  [ notice that desc is on
    the stack			]

					poke_int3_handler()

					[ int3 might be kprobe's
					  so sync events are do not
					  help ]

					-&gt; try_get_desc(descp=&amp;bp_desc)
					   desc = __READ_ONCE(bp_desc)

					   if (!desc) [false, success]
  WRITE_ONCE(bp_desc, NULL);
  atomic_dec_and_test(&amp;desc.refs)

  [ success, desc space on the stack
    is being reused and might have
    non-zero value. ]
					arch_atomic_inc_not_zero(&amp;desc-&gt;refs)

					[ might succeed since desc points to
					  stack memory that was freed and might
					  be reused. ]

Fix this issue with small backportable patch. Instead of trying to
make RCU-like behavior for bp_desc, just eliminate the unnecessary
level of indirection of bp_desc, and hold the whole descriptor as a
global.  Anyhow, there is only a single descriptor at any given
moment.

Fixes: 1f676247f36a4 ("x86/alternatives: Implement a better poke_int3_handler() completion scheme")
Signed-off-by: Nadav Amit &lt;namit@vmware.com&gt;
Signed-off-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Cc: stable@kernel.org
Link: https://lkml.kernel.org/r/20220920224743.3089-1-namit@vmware.com
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'x86_urgent_for_v6.0-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2022-09-26T21:53:38+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-09-26T21:53:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a1375562c0a87f0fa2eaf3e8ce15824696d4170a'/>
<id>a1375562c0a87f0fa2eaf3e8ce15824696d4170a</id>
<content type='text'>
Pull x86 fixes from Dave Hansen:

 - A performance fix for recent large AMD systems that avoids an ancient
   cpu idle hardware workaround

 - A new Intel model number. Folks like these upstream as soon as
   possible so that each developer doing feature development doesn't
   need to carry their own #define

 - SGX fixes for a userspace crash and a rare kernel warning

* tag 'x86_urgent_for_v6.0-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ACPI: processor idle: Practically limit "Dummy wait" workaround to old Intel systems
  x86/sgx: Handle VA page allocation failure for EAUG on PF.
  x86/sgx: Do not fail on incomplete sanitization on premature stop of ksgxd
  x86/cpu: Add CPU model numbers for Meteor Lake
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull x86 fixes from Dave Hansen:

 - A performance fix for recent large AMD systems that avoids an ancient
   cpu idle hardware workaround

 - A new Intel model number. Folks like these upstream as soon as
   possible so that each developer doing feature development doesn't
   need to carry their own #define

 - SGX fixes for a userspace crash and a rare kernel warning

* tag 'x86_urgent_for_v6.0-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ACPI: processor idle: Practically limit "Dummy wait" workaround to old Intel systems
  x86/sgx: Handle VA page allocation failure for EAUG on PF.
  x86/sgx: Do not fail on incomplete sanitization on premature stop of ksgxd
  x86/cpu: Add CPU model numbers for Meteor Lake
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'mm-hotfixes-stable-2022-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2022-09-26T20:23:15+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-09-26T20:23:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=3800a713b6070d4f03fb43613a7b7d536a99b2b7'/>
<id>3800a713b6070d4f03fb43613a7b7d536a99b2b7</id>
<content type='text'>
Pull last (?) hotfixes from Andrew Morton:
 "26 hotfixes.

  8 are for issues which were introduced during this -rc cycle, 18 are
  for earlier issues, and are cc:stable"

* tag 'mm-hotfixes-stable-2022-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (26 commits)
  x86/uaccess: avoid check_object_size() in copy_from_user_nmi()
  mm/page_isolation: fix isolate_single_pageblock() isolation behavior
  mm,hwpoison: check mm when killing accessing process
  mm/hugetlb: correct demote page offset logic
  mm: prevent page_frag_alloc() from corrupting the memory
  mm: bring back update_mmu_cache() to finish_fault()
  frontswap: don't call -&gt;init if no ops are registered
  mm/huge_memory: use pfn_to_online_page() in split_huge_pages_all()
  mm: fix madivse_pageout mishandling on non-LRU page
  powerpc/64s/radix: don't need to broadcast IPI for radix pmd collapse flush
  mm: gup: fix the fast GUP race against THP collapse
  mm: fix dereferencing possible ERR_PTR
  vmscan: check folio_test_private(), not folio_get_private()
  mm: fix VM_BUG_ON in __delete_from_swap_cache()
  tools: fix compilation after gfp_types.h split
  mm/damon/dbgfs: fix memory leak when using debugfs_lookup()
  mm/migrate_device.c: copy pte dirty bit to page
  mm/migrate_device.c: add missing flush_cache_page()
  mm/migrate_device.c: flush TLB while holding PTL
  x86/mm: disable instrumentations of mm/pgprot.c
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull last (?) hotfixes from Andrew Morton:
 "26 hotfixes.

  8 are for issues which were introduced during this -rc cycle, 18 are
  for earlier issues, and are cc:stable"

* tag 'mm-hotfixes-stable-2022-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (26 commits)
  x86/uaccess: avoid check_object_size() in copy_from_user_nmi()
  mm/page_isolation: fix isolate_single_pageblock() isolation behavior
  mm,hwpoison: check mm when killing accessing process
  mm/hugetlb: correct demote page offset logic
  mm: prevent page_frag_alloc() from corrupting the memory
  mm: bring back update_mmu_cache() to finish_fault()
  frontswap: don't call -&gt;init if no ops are registered
  mm/huge_memory: use pfn_to_online_page() in split_huge_pages_all()
  mm: fix madivse_pageout mishandling on non-LRU page
  powerpc/64s/radix: don't need to broadcast IPI for radix pmd collapse flush
  mm: gup: fix the fast GUP race against THP collapse
  mm: fix dereferencing possible ERR_PTR
  vmscan: check folio_test_private(), not folio_get_private()
  mm: fix VM_BUG_ON in __delete_from_swap_cache()
  tools: fix compilation after gfp_types.h split
  mm/damon/dbgfs: fix memory leak when using debugfs_lookup()
  mm/migrate_device.c: copy pte dirty bit to page
  mm/migrate_device.c: add missing flush_cache_page()
  mm/migrate_device.c: flush TLB while holding PTL
  x86/mm: disable instrumentations of mm/pgprot.c
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/uaccess: avoid check_object_size() in copy_from_user_nmi()</title>
<updated>2022-09-26T19:14:35+00:00</updated>
<author>
<name>Kees Cook</name>
<email>keescook@chromium.org</email>
</author>
<published>2022-09-19T20:16:48+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=59298997df89e19aad426d4ae0a7e5037074da5a'/>
<id>59298997df89e19aad426d4ae0a7e5037074da5a</id>
<content type='text'>
The check_object_size() helper under CONFIG_HARDENED_USERCOPY is designed
to skip any checks where the length is known at compile time as a
reasonable heuristic to avoid "likely known-good" cases.  However, it can
only do this when the copy_*_user() helpers are, themselves, inline too.

Using find_vmap_area() requires taking a spinlock.  The
check_object_size() helper can call find_vmap_area() when the destination
is in vmap memory.  If show_regs() is called in interrupt context, it will
attempt a call to copy_from_user_nmi(), which may call check_object_size()
and then find_vmap_area().  If something in normal context happens to be
in the middle of calling find_vmap_area() (with the spinlock held), the
interrupt handler will hang forever.

The copy_from_user_nmi() call is actually being called with a fixed-size
length, so check_object_size() should never have been called in the first
place.  Given the narrow constraints, just replace the
__copy_from_user_inatomic() call with an open-coded version that calls
only into the sanitizers and not check_object_size(), followed by a call
to raw_copy_from_user().

[akpm@linux-foundation.org: no instrument_copy_from_user() in my tree...]
Link: https://lkml.kernel.org/r/20220919201648.2250764-1-keescook@chromium.org
Link: https://lore.kernel.org/all/CAOUHufaPshtKrTWOz7T7QFYUNVGFm0JBjvM700Nhf9qEL9b3EQ@mail.gmail.com
Fixes: 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns")
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Reported-by: Yu Zhao &lt;yuzhao@google.com&gt;
Reported-by: Florian Lehner &lt;dev@der-flo.net&gt;
Suggested-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Acked-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Tested-by: Florian Lehner &lt;dev@der-flo.net&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: Josh Poimboeuf &lt;jpoimboe@kernel.org&gt;
Cc: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The check_object_size() helper under CONFIG_HARDENED_USERCOPY is designed
to skip any checks where the length is known at compile time as a
reasonable heuristic to avoid "likely known-good" cases.  However, it can
only do this when the copy_*_user() helpers are, themselves, inline too.

Using find_vmap_area() requires taking a spinlock.  The
check_object_size() helper can call find_vmap_area() when the destination
is in vmap memory.  If show_regs() is called in interrupt context, it will
attempt a call to copy_from_user_nmi(), which may call check_object_size()
and then find_vmap_area().  If something in normal context happens to be
in the middle of calling find_vmap_area() (with the spinlock held), the
interrupt handler will hang forever.

The copy_from_user_nmi() call is actually being called with a fixed-size
length, so check_object_size() should never have been called in the first
place.  Given the narrow constraints, just replace the
__copy_from_user_inatomic() call with an open-coded version that calls
only into the sanitizers and not check_object_size(), followed by a call
to raw_copy_from_user().

[akpm@linux-foundation.org: no instrument_copy_from_user() in my tree...]
Link: https://lkml.kernel.org/r/20220919201648.2250764-1-keescook@chromium.org
Link: https://lore.kernel.org/all/CAOUHufaPshtKrTWOz7T7QFYUNVGFm0JBjvM700Nhf9qEL9b3EQ@mail.gmail.com
Fixes: 0aef499f3172 ("mm/usercopy: Detect vmalloc overruns")
Signed-off-by: Kees Cook &lt;keescook@chromium.org&gt;
Reported-by: Yu Zhao &lt;yuzhao@google.com&gt;
Reported-by: Florian Lehner &lt;dev@der-flo.net&gt;
Suggested-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Acked-by: Peter Zijlstra (Intel) &lt;peterz@infradead.org&gt;
Tested-by: Florian Lehner &lt;dev@der-flo.net&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: Josh Poimboeuf &lt;jpoimboe@kernel.org&gt;
Cc: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm</title>
<updated>2022-09-23T15:42:30+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2022-09-23T15:42:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=317fab7ec55d5a150bce46f37efbc942013a8c5b'/>
<id>317fab7ec55d5a150bce46f37efbc942013a8c5b</id>
<content type='text'>
Pull kvm fixes from Paolo Bonzini:
 "As everyone back came back from conferences, here are the pending
  patches for Linux 6.0.

  ARM:

   - Fix for kmemleak with pKVM

  s390:

   - Fixes for VFIO with zPCI

   - smatch fix

  x86:

   - Ensure XSAVE-capable hosts always allow FP and SSE state to be
     saved and restored via KVM_{GET,SET}_XSAVE

   - Fix broken max_mmu_rmap_size stat

   - Fix compile error with old glibc that doesn't have gettid()"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: Inject #UD on emulated XSETBV if XSAVES isn't enabled
  KVM: x86: Always enable legacy FP/SSE in allowed user XFEATURES
  KVM: x86: Reinstate kvm_vcpu_arch.guest_supported_xcr0
  KVM: x86/mmu: add missing update to max_mmu_rmap_size
  selftests: kvm: Fix a compile error in selftests/kvm/rseq_test.c
  KVM: s390: pci: register pci hooks without interpretation
  KVM: s390: pci: fix GAIT physical vs virtual pointers usage
  KVM: s390: Pass initialized arg even if unused
  KVM: s390: pci: fix plain integer as NULL pointer warnings
  KVM: arm64: Use kmemleak_free_part_phys() to unregister hyp_mem_base
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull kvm fixes from Paolo Bonzini:
 "As everyone back came back from conferences, here are the pending
  patches for Linux 6.0.

  ARM:

   - Fix for kmemleak with pKVM

  s390:

   - Fixes for VFIO with zPCI

   - smatch fix

  x86:

   - Ensure XSAVE-capable hosts always allow FP and SSE state to be
     saved and restored via KVM_{GET,SET}_XSAVE

   - Fix broken max_mmu_rmap_size stat

   - Fix compile error with old glibc that doesn't have gettid()"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: Inject #UD on emulated XSETBV if XSAVES isn't enabled
  KVM: x86: Always enable legacy FP/SSE in allowed user XFEATURES
  KVM: x86: Reinstate kvm_vcpu_arch.guest_supported_xcr0
  KVM: x86/mmu: add missing update to max_mmu_rmap_size
  selftests: kvm: Fix a compile error in selftests/kvm/rseq_test.c
  KVM: s390: pci: register pci hooks without interpretation
  KVM: s390: pci: fix GAIT physical vs virtual pointers usage
  KVM: s390: Pass initialized arg even if unused
  KVM: s390: pci: fix plain integer as NULL pointer warnings
  KVM: arm64: Use kmemleak_free_part_phys() to unregister hyp_mem_base
</pre>
</div>
</content>
</entry>
</feed>
