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4 Commits

Author SHA1 Message Date
Dr. David Alan Gilbert
597da28e1a mm/page_table_check.c: use strtobool for param parsing 
Use strtobool rather than open coding "on" and "off" parsing.

Link: https://lkml.kernel.org/r/20220227181038.126926-1-linux@treblig.org
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-03-22 15:57:11 -07:00
Pasha Tatashin
80110bbfbb mm/page_table_check: check entries at pmd levels 
syzbot detected a case where the page table counters were not properly
updated.

  syzkaller login:  ------------[ cut here ]------------
  kernel BUG at mm/page_table_check.c:162!
  invalid opcode: 0000 [#1] PREEMPT SMP KASAN
  CPU: 0 PID: 3099 Comm: pasha Not tainted 5.16.0+ #48
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIO4
  RIP: 0010:__page_table_check_zero+0x159/0x1a0
  Call Trace:
   free_pcp_prepare+0x3be/0xaa0
   free_unref_page+0x1c/0x650
   free_compound_page+0xec/0x130
   free_transhuge_page+0x1be/0x260
   __put_compound_page+0x90/0xd0
   release_pages+0x54c/0x1060
   __pagevec_release+0x7c/0x110
   shmem_undo_range+0x85e/0x1250
  ...

The repro involved having a huge page that is split due to uprobe event
temporarily replacing one of the pages in the huge page.  Later the huge
page was combined again, but the counters were off, as the PTE level was
not properly updated.

Make sure that when PMD is cleared and prior to freeing the level the
PTEs are updated.

Link: https://lkml.kernel.org/r/20220131203249.2832273-5-pasha.tatashin@soleen.com
Fixes: df4e817b71 ("mm: page table check")
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Paul Turner <pjt@google.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-02-04 09:25:04 -08:00
Pasha Tatashin
64d8b9e145 mm/page_table_check: use unsigned long for page counters and cleanup 
For consistency, use "unsigned long" for all page counters.

Also, reduce code duplication by calling __page_table_check_*_clear()
from __page_table_check_*_set() functions.

Link: https://lkml.kernel.org/r/20220131203249.2832273-3-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Wei Xu <weixugc@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Paul Turner <pjt@google.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-02-04 09:25:04 -08:00
Pasha Tatashin
df4e817b71 mm: page table check 
Check user page table entries at the time they are added and removed.

Allows to synchronously catch memory corruption issues related to double
mapping.

When a pte for an anonymous page is added into page table, we verify
that this pte does not already point to a file backed page, and vice
versa if this is a file backed page that is being added we verify that
this page does not have an anonymous mapping

We also enforce that read-only sharing for anonymous pages is allowed
(i.e.  cow after fork).  All other sharing must be for file pages.

Page table check allows to protect and debug cases where "struct page"
metadata became corrupted for some reason.  For example, when refcnt or
mapcount become invalid.

Link: https://lkml.kernel.org/r/20211221154650.1047963-4-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Xu <weixugc@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
 2022-01-15 16:30:28 +02:00