• Jan Beulich's avatar
    x86/mm/xen: Suppress hugetlbfs in PV guests · b0363263
    Jan Beulich authored
    commit 103f6112 upstream.
    
    Huge pages are not normally available to PV guests. Not suppressing
    hugetlbfs use results in an endless loop of page faults when user mode
    code tries to access a hugetlbfs mapped area (since the hypervisor
    denies such PTEs to be created, but error indications can't be
    propagated out of xen_set_pte_at(), just like for various of its
    siblings), and - once killed in an oops like this:
    
      kernel BUG at .../fs/hugetlbfs/inode.c:428!
      invalid opcode: 0000 [#1] SMP
      ...
      RIP: e030:[<ffffffff811c333b>]  [<ffffffff811c333b>] remove_inode_hugepages+0x25b/0x320
      ...
      Call Trace:
       [<ffffffff811c3415>] hugetlbfs_evict_inode+0x15/0x40
       [<ffffffff81167b3d>] evict+0xbd/0x1b0
       [<ffffffff8116514a>] __dentry_kill+0x19a/0x1f0
       [<ffffffff81165b0e>] dput+0x1fe/0x220
       [<ffffffff81150535>] __fput+0x155/0x200
       [<ffffffff81079fc0>] task_work_run+0x60/0xa0
       [<ffffffff81063510>] do_exit+0x160/0x400
       [<ffffffff810637eb>] do_group_exit+0x3b/0xa0
       [<ffffffff8106e8bd>] get_signal+0x1ed/0x470
       [<ffffffff8100f854>] do_signal+0x14/0x110
       [<ffffffff810030e9>] prepare_exit_to_usermode+0xe9/0xf0
       [<ffffffff814178a5>] retint_user+0x8/0x13
    
    This is CVE-2016-3961 / XSA-174.
    Reported-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
    Signed-off-by: default avatarJan Beulich <jbeulich@suse.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: David Vrabel <david.vrabel@citrix.com>
    Cc: Denys Vlasenko <dvlasenk@redhat.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Juergen Gross <JGross@suse.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Luis R. Rodriguez <mcgrof@suse.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Toshi Kani <toshi.kani@hp.com>
    Cc: xen-devel <xen-devel@lists.xenproject.org>
    Link: http://lkml.kernel.org/r/57188ED802000078000E431C@prv-mh.provo.novell.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
    Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
    b0363263
hugetlb.h 2.19 KB