[PULL 11/24] hw/usb/hcd-xhci: Check whether DMA accesses fail

[Gerd Hoffmann <kraxel@redhat.com>]

From: Thomas Huth <thuth@redhat.com>

If a guest sets up bad descriptors, it could force QEMU to access
non-existing memory regions. Thus we should check the return value
of dma_memory_read/write() to make sure that these errors don't go
unnoticed.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220817160016.49752-1-thuth@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/hcd-xhci.c | 64 +++++++++++++++++++++++++++++++++++------------
 1 file changed, 48 insertions(+), 16 deletions(-)

diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 3c48b58ddeb5..acd60b1a4904 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -463,6 +463,12 @@ static void xhci_mfwrap_timer(void *opaque)
     xhci_mfwrap_update(xhci);
 }
 
+static void xhci_die(XHCIState *xhci)
+{
+    xhci->usbsts |= USBSTS_HCE;
+    DPRINTF("xhci: asserted controller error\n");
+}
+
 static inline dma_addr_t xhci_addr64(uint32_t low, uint32_t high)
 {
     if (sizeof(dma_addr_t) == 4) {
@@ -488,7 +494,14 @@ static inline void xhci_dma_read_u32s(XHCIState *xhci, dma_addr_t addr,
 
     assert((len % sizeof(uint32_t)) == 0);
 
-    dma_memory_read(xhci->as, addr, buf, len, MEMTXATTRS_UNSPECIFIED);
+    if (dma_memory_read(xhci->as, addr, buf, len,
+                        MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: DMA memory access failed!\n",
+                      __func__);
+        memset(buf, 0xff, len);
+        xhci_die(xhci);
+        return;
+    }
 
     for (i = 0; i < (len / sizeof(uint32_t)); i++) {
         buf[i] = le32_to_cpu(buf[i]);
@@ -496,7 +509,7 @@ static inline void xhci_dma_read_u32s(XHCIState *xhci, dma_addr_t addr,
 }
 
 static inline void xhci_dma_write_u32s(XHCIState *xhci, dma_addr_t addr,
-                                       uint32_t *buf, size_t len)
+                                       const uint32_t *buf, size_t len)
 {
     int i;
     uint32_t tmp[5];
@@ -508,7 +521,13 @@ static inline void xhci_dma_write_u32s(XHCIState *xhci, dma_addr_t addr,
     for (i = 0; i < n; i++) {
         tmp[i] = cpu_to_le32(buf[i]);
     }
-    dma_memory_write(xhci->as, addr, tmp, len, MEMTXATTRS_UNSPECIFIED);
+    if (dma_memory_write(xhci->as, addr, tmp, len,
+                         MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: DMA memory access failed!\n",
+                      __func__);
+        xhci_die(xhci);
+        return;
+    }
 }
 
 static XHCIPort *xhci_lookup_port(XHCIState *xhci, struct USBPort *uport)
@@ -593,12 +612,6 @@ static inline int xhci_running(XHCIState *xhci)
     return !(xhci->usbsts & USBSTS_HCH);
 }
 
-static void xhci_die(XHCIState *xhci)
-{
-    xhci->usbsts |= USBSTS_HCE;
-    DPRINTF("xhci: asserted controller error\n");
-}
-
 static void xhci_write_event(XHCIState *xhci, XHCIEvent *event, int v)
 {
     XHCIInterrupter *intr = &xhci->intr[v];
@@ -619,7 +632,12 @@ static void xhci_write_event(XHCIState *xhci, XHCIEvent *event, int v)
                                ev_trb.status, ev_trb.control);
 
     addr = intr->er_start + TRB_SIZE*intr->er_ep_idx;
-    dma_memory_write(xhci->as, addr, &ev_trb, TRB_SIZE, MEMTXATTRS_UNSPECIFIED);
+    if (dma_memory_write(xhci->as, addr, &ev_trb, TRB_SIZE,
+                         MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: DMA memory access failed!\n",
+                      __func__);
+        xhci_die(xhci);
+    }
 
     intr->er_ep_idx++;
     if (intr->er_ep_idx >= intr->er_size) {
@@ -680,8 +698,12 @@ static TRBType xhci_ring_fetch(XHCIState *xhci, XHCIRing *ring, XHCITRB *trb,
 
     while (1) {
         TRBType type;
-        dma_memory_read(xhci->as, ring->dequeue, trb, TRB_SIZE,
-                        MEMTXATTRS_UNSPECIFIED);
+        if (dma_memory_read(xhci->as, ring->dequeue, trb, TRB_SIZE,
+                            MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: DMA memory access failed!\n",
+                          __func__);
+            return 0;
+        }
         trb->addr = ring->dequeue;
         trb->ccs = ring->ccs;
         le64_to_cpus(&trb->parameter);
@@ -798,8 +820,14 @@ static void xhci_er_reset(XHCIState *xhci, int v)
         xhci_die(xhci);
         return;
     }
-    dma_memory_read(xhci->as, erstba, &seg, sizeof(seg),
-                    MEMTXATTRS_UNSPECIFIED);
+    if (dma_memory_read(xhci->as, erstba, &seg, sizeof(seg),
+                    MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: DMA memory access failed!\n",
+                      __func__);
+        xhci_die(xhci);
+        return;
+    }
+
     le32_to_cpus(&seg.addr_low);
     le32_to_cpus(&seg.addr_high);
     le32_to_cpus(&seg.size);
@@ -2415,8 +2443,12 @@ static TRBCCode xhci_get_port_bandwidth(XHCIState *xhci, uint64_t pctx)
     /* TODO: actually implement real values here */
     bw_ctx[0] = 0;
     memset(&bw_ctx[1], 80, xhci->numports); /* 80% */
-    dma_memory_write(xhci->as, ctx, bw_ctx, sizeof(bw_ctx),
-                     MEMTXATTRS_UNSPECIFIED);
+    if (dma_memory_write(xhci->as, ctx, bw_ctx, sizeof(bw_ctx),
+                     MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s: DMA memory write failed!\n",
+                      __func__);
+        return CC_TRB_ERROR;
+    }
 
     return CC_SUCCESS;
 }
-- 
2.37.3