From: Joerg Roedel <jroedel@xxxxxxx> [ 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@xxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Tested-by: David H. Gutteridge <dhgutteridge@xxxxxxxxxxxx> Cc: "H . Peter Anvin" <hpa@xxxxxxxxx> Cc: linux-mm@xxxxxxxxx Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxx> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Jiri Kosina <jkosina@xxxxxxx> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: David Laight <David.Laight@xxxxxxxxxx> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx> Cc: Eduardo Valentin <eduval@xxxxxxxxxx> Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Will Deacon <will.deacon@xxxxxxx> Cc: aliguori@xxxxxxxxxx Cc: daniel.gruss@xxxxxxxxxxxxxx Cc: hughd@xxxxxxxxxx Cc: keescook@xxxxxxxxxx Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Waiman Long <llong@xxxxxxxxxx> Cc: Pavel Machek <pavel@xxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Namhyung Kim <namhyung@xxxxxxxxxx> Cc: joro@xxxxxxxxxx Link: https://lkml.kernel.org/r/1532533683-5988-4-git-send-email-joro@xxxxxxxxxx Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- 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 d1ab07ec8c9a..5409c2800ab5 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); -- 2.17.1
