[Xen-changelog] [qemu-xen-traditional stable-4.7] xen: fix ioreq handling

[patchbot@xxxxxxx]

commit 02a1797276642b9ba4f43c919da49767428877e7
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Nov 29 16:36:38 2016 +0000
Commit:     Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
CommitDate: Tue Nov 29 18:37:02 2016 +0000

    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: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
    (cherry picked from commit 89c4cbe8d234049b0145e4dc5e5d19d626250b57)
---
 i386-dm/helper2.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/i386-dm/helper2.c b/i386-dm/helper2.c
index 2706f2e..329d25b 100644
--- a/i386-dm/helper2.c
+++ b/i386-dm/helper2.c
@@ -375,6 +375,11 @@ static void cpu_ioreq_pio(CPUState *env, ioreq_t *req)
 {
     uint32_t i;
 
+    if (req->size > sizeof(unsigned long)) {
+        fprintf(stderr, "PIO: bad size (%u)\n", req->size);
+        exit(-1);
+    }
+
     if (req->dir == IOREQ_READ) {
         if (!req->data_is_ptr) {
             req->data = do_inp(env, req->addr, req->size);
@@ -404,6 +409,11 @@ static void cpu_ioreq_move(CPUState *env, ioreq_t *req)
 {
     uint32_t i;
 
+    if (req->size > sizeof(req->data)) {
+        fprintf(stderr, "MMIO: bad size (%u)\n", req->size);
+        exit(-1);
+    }
+
     if (!req->data_is_ptr) {
         if (req->dir == IOREQ_READ) {
             for (i = 0; i < req->count; i++) {
@@ -516,11 +526,13 @@ static int __handle_buffered_iopage(CPUState *env)
         req.df = 1;
         req.type = buf_req->type;
         req.data_is_ptr = 0;
+        xen_rmb();
         qw = (req.size == 8);
         if (qw) {
             buf_req = &buffered_io_page->buf_ioreq[(rdptr + 1) %
                                                    IOREQ_BUFFER_SLOT_NUM];
             req.data |= ((uint64_t)buf_req->data) << 32;
+            xen_rmb();
         }
 
         __handle_ioreq(env, &req);
@@ -552,7 +564,11 @@ static void cpu_handle_ioreq(void *opaque)
 
     __handle_buffered_iopage(env);
     if (req) {
-        __handle_ioreq(env, req);
+        ioreq_t copy = *req;
+
+        xen_rmb();
+        __handle_ioreq(env, &copy);
+        req->data = copy.data;
 
         if (req->state != STATE_IOREQ_INPROCESS) {
             fprintf(logfile, "Badness in I/O request ... not in service?!: "
--
generated by git-patchbot for /home/xen/git/qemu-xen-traditional.git#stable-4.7

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