[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86/grant: disallow misaligned PTEs
commit ce442926c2530da9376199dcc769436376ad2386 Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> AuthorDate: Tue Aug 15 15:06:45 2017 +0200 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Tue Aug 15 15:06:45 2017 +0200 x86/grant: disallow misaligned PTEs Pagetable entries must be aligned to function correctly. Disallow attempts from the guest to have a grant PTE created at a misaligned address, which would result in corruption of the L1 table with largely-guest-controlled values. This is CVE-2017-12137 / XSA-227. Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> --- xen/arch/x86/mm.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index f53ca43..5b863c6 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -3767,6 +3767,9 @@ static int create_grant_pte_mapping( l1_pgentry_t ol1e; struct domain *d = v->domain; + if ( !IS_ALIGNED(pte_addr, sizeof(nl1e)) ) + return GNTST_general_error; + adjust_guest_l1e(nl1e, d); gmfn = pte_addr >> PAGE_SHIFT; @@ -3823,6 +3826,16 @@ static int destroy_grant_pte_mapping( struct page_info *page; l1_pgentry_t ol1e; + /* + * addr comes from Xen's active_entry tracking so isn't guest controlled, + * but it had still better be PTE-aligned. + */ + if ( !IS_ALIGNED(addr, sizeof(ol1e)) ) + { + ASSERT_UNREACHABLE(); + return GNTST_general_error; + } + gmfn = addr >> PAGE_SHIFT; page = get_page_from_gfn(d, gmfn, NULL, P2M_ALLOC); -- generated by git-patchbot for /home/xen/git/xen.git#master _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxx https://lists.xenproject.org/xen-changelog
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