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xen: fix ioreq handling

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

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

Reported-by: yanghongke <yanghongke@huawei.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
This commit is contained in:
Jan Beulich 2016-11-22 05:56:51 -07:00 committed by Stefano Stabellini
parent a7764f1548
commit b85f9dfdb1
1 changed files with 15 additions and 1 deletions
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16
xen-hvm.c
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@ -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?!: "