On Mon, 17 Sep 2018, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > This is a note to let you know that I've just added the patch titled > > x86/kexec: Allocate 8k PGDs for PTI > > to the 3.18-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > x86-kexec-allocate-8k-pgds-for-pti.patch > and it can be found in the queue-3.18 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable@xxxxxxxxxxxxxxx> know about it. I believe this commit is an example of the auto-selector being too eager, and this should not be in *any* of the stable trees. As the commit message indicates, it's a fix by Joerg for his PTI-x86-32 implementation - which has not been backported to any of the stable trees (yet), has it? In several of the recent stable trees, I think this will not do any actual harm; but it looks as if it will prevent relevant x86-32 configs from building on 3.18 (I see no definition of PGD_ALLOCATION_ORDER in linux-3.18.y - you preferred not to have any PTI in that tree), and I haven't checked whether its definition in older backports will build correctly here or not. Hugh > > > From foo@baz Mon Sep 17 11:45:57 CEST 2018 > From: Joerg Roedel <jroedel@xxxxxxx> > Date: Wed, 25 Jul 2018 17:48:03 +0200 > Subject: x86/kexec: Allocate 8k PGDs for PTI > > 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> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > --- > arch/x86/kernel/machine_kexec_32.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > --- a/arch/x86/kernel/machine_kexec_32.c > +++ b/arch/x86/kernel/machine_kexec_32.c > @@ -69,7 +69,7 @@ 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); > @@ -85,7 +85,8 @@ static void machine_kexec_free_page_tabl > > 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); > > > Patches currently in stable-queue which might be from jroedel@xxxxxxx are > > queue-3.18/x86-kexec-allocate-8k-pgds-for-pti.patch > queue-3.18/x86-mm-remove-in_nmi-warning-from-vmalloc_fault.patch >
