From: Joerg Roedel jroedel@suse.de
[ Upstream commit ca38dc8f2724d101038b1205122c93a1c7f38f11 ]
Fuzzing the PTI-x86-32 code with trinity showed unhandled kernel paging request oops-messages that looked a lot like silent data corruption.
Lot's of debugging and testing lead to the kexec-32bit code, which is still allocating 4k PGDs when PTI is enabled. But since it uses native_set_pud() to build the page-table, it will unevitably call into __pti_set_user_pgtbl(), which writes beyond the allocated 4k page.
Use PGD_ALLOCATION_ORDER to allocate PGDs in the kexec code to fix the issue.
Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: David H. Gutteridge dhgutteridge@sympatico.ca 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: Pavel Machek pavel@ucw.cz Cc: Arnaldo Carvalho de Melo acme@kernel.org Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Jiri Olsa jolsa@redhat.com Cc: Namhyung Kim namhyung@kernel.org Cc: joro@8bytes.org Link: https://lkml.kernel.org/r/1532533683-5988-4-git-send-email-joro@8bytes.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/x86/kernel/machine_kexec_32.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c index 5167f3f74136..83cb5f3c72e5 100644 --- a/arch/x86/kernel/machine_kexec_32.c +++ b/arch/x86/kernel/machine_kexec_32.c @@ -56,7 +56,7 @@ static void load_segments(void)
static void machine_kexec_free_page_tables(struct kimage *image) { - free_page((unsigned long)image->arch.pgd); + free_pages((unsigned long)image->arch.pgd, PGD_ALLOCATION_ORDER); image->arch.pgd = NULL; #ifdef CONFIG_X86_PAE free_page((unsigned long)image->arch.pmd0); @@ -72,7 +72,8 @@ static void machine_kexec_free_page_tables(struct kimage *image)
static int machine_kexec_alloc_page_tables(struct kimage *image) { - image->arch.pgd = (pgd_t *)get_zeroed_page(GFP_KERNEL); + image->arch.pgd = (pgd_t *)__get_free_pages(GFP_KERNEL | __GFP_ZERO, + PGD_ALLOCATION_ORDER); #ifdef CONFIG_X86_PAE image->arch.pmd0 = (pmd_t *)get_zeroed_page(GFP_KERNEL); image->arch.pmd1 = (pmd_t *)get_zeroed_page(GFP_KERNEL);