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    Subject[ 43/56] Yama: handle 32-bit userspace prctl
    Date
    3.6-stable review patch.  If anyone has any objections, please let me know.

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

    From: Kees Cook <keescook@chromium.org>

    commit 2e4930eb7c8fb20a39dfb5f8a8f80402710dcea8 upstream.

    When running a 64-bit kernel and receiving prctls from a 32-bit
    userspace, the "-1" used as an unsigned long will end up being
    misdetected. The kernel is looking for 0xffffffffffffffff instead of
    0xffffffff. Since prctl lacks a distinct compat interface, Yama needs
    to handle this translation itself. As such, support either value as
    meaning PR_SET_PTRACER_ANY, to avoid breaking the ABI for 64-bit.

    Signed-off-by: Kees Cook <keescook@chromium.org>
    Acked-by: John Johansen <john.johansen@canonical.com>
    Signed-off-by: James Morris <james.l.morris@oracle.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    security/yama/yama_lsm.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/security/yama/yama_lsm.c
    +++ b/security/yama/yama_lsm.c
    @@ -143,7 +143,7 @@ static int yama_task_prctl(int option, u
    if (arg2 == 0) {
    yama_ptracer_del(NULL, myself);
    rc = 0;
    - } else if (arg2 == PR_SET_PTRACER_ANY) {
    + } else if (arg2 == PR_SET_PTRACER_ANY || (int)arg2 == -1) {
    rc = yama_ptracer_add(NULL, myself);
    } else {
    struct task_struct *tracer;



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