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    Subject[PATCH 3.16 216/357] x86/kaslr: Avoid the setup_data area when picking location
    Date
    3.16-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Kees Cook <keescook@chromium.org>

    commit 0cacbfbeb5077b63d5d3cf6df88b14ac12ad584b upstream.

    The KASLR location-choosing logic needs to avoid the setup_data
    list memory areas as well. Without this, it would be possible to
    have the ASLR position stomp on the memory, ultimately causing
    the boot to fail.

    Signed-off-by: Kees Cook <keescook@chromium.org>
    Tested-by: Baoquan He <bhe@redhat.com>
    Cc: Vivek Goyal <vgoyal@redhat.com>
    Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    Cc: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
    Cc: Pavel Machek <pavel@ucw.cz>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Link: http://lkml.kernel.org/r/20140911161931.GA12001@www.outflux.net
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/boot/compressed/aslr.c | 15 +++++++++++++++
    1 file changed, 15 insertions(+)

    --- a/arch/x86/boot/compressed/aslr.c
    +++ b/arch/x86/boot/compressed/aslr.c
    @@ -183,12 +183,27 @@ static void mem_avoid_init(unsigned long
    static bool mem_avoid_overlap(struct mem_vector *img)
    {
    int i;
    + struct setup_data *ptr;

    for (i = 0; i < MEM_AVOID_MAX; i++) {
    if (mem_overlaps(img, &mem_avoid[i]))
    return true;
    }

    + /* Avoid all entries in the setup_data linked list. */
    + ptr = (struct setup_data *)(unsigned long)real_mode->hdr.setup_data;
    + while (ptr) {
    + struct mem_vector avoid;
    +
    + avoid.start = (u64)ptr;
    + avoid.size = sizeof(*ptr) + ptr->len;
    +
    + if (mem_overlaps(img, &avoid))
    + return true;
    +
    + ptr = (struct setup_data *)(unsigned long)ptr->next;
    + }
    +
    return false;
    }




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