Commit b85f9dfd authored by Jan Beulich's avatar Jan Beulich Committed by Stefano Stabellini
Browse files

xen: fix ioreq handling 



Avoid double fetches and bounds check size to avoid overflowing
internal variables.

This is CVE-2016-9381 / XSA-197.

Reported-by: default avataryanghongke <yanghongke@huawei.com>
Signed-off-by: default avatarJan Beulich <jbeulich@suse.com>
Reviewed-by: default avatarStefano Stabellini <sstabellini@kernel.org>
Signed-off-by: default avatarStefano Stabellini <sstabellini@kernel.org>
parent a7764f15

xen-hvm.c

+15 −1
Original line number Diff line number Diff line
@@ -810,6 +810,10 @@ static void cpu_ioreq_pio(ioreq_t *req) 
    trace_cpu_ioreq_pio(req, req->dir, req->df, req->data_is_ptr, req->addr,

                         req->data, req->count, req->size);



    if (req->size > sizeof(uint32_t)) {

        hw_error("PIO: bad size (%u)", req->size);

    }



    if (req->dir == IOREQ_READ) {

        if (!req->data_is_ptr) {

            req->data = do_inp(req->addr, req->size);
@@ -846,6 +850,10 @@ static void cpu_ioreq_move(ioreq_t *req) 
    trace_cpu_ioreq_move(req, req->dir, req->df, req->data_is_ptr, req->addr,

                         req->data, req->count, req->size);



    if (req->size > sizeof(req->data)) {

        hw_error("MMIO: bad size (%u)", req->size);

    }



    if (!req->data_is_ptr) {

        if (req->dir == IOREQ_READ) {

            for (i = 0; i < req->count; i++) {
@@ -1010,11 +1018,13 @@ static int handle_buffered_iopage(XenIOState *state) 
        req.df = 1;

        req.type = buf_req->type;

        req.data_is_ptr = 0;

        xen_rmb();

        qw = (req.size == 8);

        if (qw) {

            buf_req = &buf_page->buf_ioreq[(rdptr + 1) %

                                           IOREQ_BUFFER_SLOT_NUM];

            req.data |= ((uint64_t)buf_req->data) << 32;

            xen_rmb();

        }



        handle_ioreq(state, &req);
@@ -1045,7 +1055,11 @@ static void cpu_handle_ioreq(void *opaque) 


    handle_buffered_iopage(state);

    if (req) {

        handle_ioreq(state, req);

        ioreq_t copy = *req;



        xen_rmb();

        handle_ioreq(state, &copy);

        req->data = copy.data;



        if (req->state != STATE_IOREQ_INPROCESS) {

            fprintf(stderr, "Badness in I/O request ... not in service?!: "