[PATCH] hw/usb/hcd-xhci: Fix guest-triggerable assert() in xhci_find_stream()

[Thomas Huth <thuth@redhat.com>]

From: Thomas Huth <thuth@redhat.com>

The assert() statement in xhci_find_stream() can be triggered by
the guest (see bug tickets #273, #3895 and #3988 on gitlab.com).
Turn it into a qemu_log_mask() instead to fix this problem.

Resolves: https://gitlab.com/qemu-project/qemu/-/work_items/273
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 hw/usb/hcd-xhci.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index c7e050e38fd..ae8add4227e 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -1009,7 +1009,12 @@ static XHCIStreamContext *xhci_find_stream(XHCIEPContext *epctx,
     dma_addr_t base;
     uint32_t ctx[2], sct;
 
-    assert(streamid != 0);
+    if (!streamid) {
+        qemu_log_mask(LOG_GUEST_ERROR, "xhci: stream ID is zero\n");
+        *cc_error = CC_INVALID_STREAM_ID_ERROR;
+        return NULL;
+    }
+
     if (epctx->lsa) {
         if (streamid >= epctx->nr_pstreams) {
             *cc_error = CC_INVALID_STREAM_ID_ERROR;
-- 
2.55.0