[Xen-changelog] [qemu-xen stable-4.6] xen: fix ioreq handling

[patchbot@xxxxxxx]

commit ba9175c5bde6796851d3b9d888ee488fd0257d05
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Nov 22 11:13:00 2016 -0800
Commit:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
CommitDate: Tue Nov 22 11:13:00 2016 -0800

    xen: fix ioreq handling
    
    Avoid double fetches and bounds check size to avoid overflowing
    internal variables.
    
    This is XSA-197.
    
    Reported-by: yanghongke <yanghongke@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 xen-hvm.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/xen-hvm.c b/xen-hvm.c
index 4a215e3..9f01f41 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -817,6 +817,10 @@ static void cpu_ioreq_pio(ioreq_t *req)
 {
     uint32_t i;
 
+    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)
 {
     uint32_t i;
 
+    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++) {
@@ -999,11 +1007,13 @@ 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);
@@ -1034,7 +1044,11 @@ 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?!: "
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#stable-4.6

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