4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Joerg Roedel jroedel@suse.de
[ Upstream commit 935232ce28dfabff1171e5a7113b2d865fa9ee63 ]
The addr counter will overflow if the last PMD of the address space is cloned, resulting in an endless loop.
Check for that and bail out of the loop when it happens.
Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Pavel Machek pavel@ucw.cz Cc: "H . Peter Anvin" hpa@zytor.com Cc: linux-mm@kvack.org Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Andy Lutomirski luto@kernel.org Cc: Dave Hansen dave.hansen@intel.com Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Juergen Gross jgross@suse.com Cc: Peter Zijlstra peterz@infradead.org Cc: Borislav Petkov bp@alien8.de Cc: Jiri Kosina jkosina@suse.cz Cc: Boris Ostrovsky boris.ostrovsky@oracle.com Cc: Brian Gerst brgerst@gmail.com Cc: David Laight David.Laight@aculab.com Cc: Denys Vlasenko dvlasenk@redhat.com Cc: Eduardo Valentin eduval@amazon.com Cc: Greg KH gregkh@linuxfoundation.org Cc: Will Deacon will.deacon@arm.com Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: Andrea Arcangeli aarcange@redhat.com Cc: Waiman Long llong@redhat.com Cc: "David H . Gutteridge" dhgutteridge@sympatico.ca Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1531906876-13451-25-git-send-email-joro@8bytes.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/mm/pti.c | 4 ++++ 1 file changed, 4 insertions(+)
--- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -306,6 +306,10 @@ pti_clone_pmds(unsigned long start, unsi p4d_t *p4d; pud_t *pud;
+ /* Overflow check */ + if (addr < start) + break; + pgd = pgd_offset_k(addr); if (WARN_ON(pgd_none(*pgd))) return;