Commit bf10c11af5 for qemu.org

commit bf10c11af515e7de6343a429f9d6b505c504d531
Author: Thanos Makatos <thanos.makatos@nutanix.com>
Date:   Tue Jul 21 12:27:00 2026 +0000

    vfio-user: vfio_user_device_io_set_irqs: prevent buffer overflow

    This isn't in practise a problem since irq->argsz is not
    externally provided, it's a good hardening step nonetheless.

    Fixes: ca1add1696 ("vfio-user: implement VFIO_USER_DEVICE_GET/SET_IRQ*")
    Signed-off-by: Thanos Makatos <thanos.makatos@nutanix.com>
    Reviewed-by: Cédric Le Goater <clg@redhat.com>
    Link: https://lore.kernel.org/qemu-devel/20260721122643.30985-9-thanos.makatos@nutanix.com
    Signed-off-by: Cédric Le Goater <clg@redhat.com>

diff --git a/hw/vfio-user/device.c b/hw/vfio-user/device.c
index 8feaa56875..daac0e21b6 100644
--- a/hw/vfio-user/device.c
+++ b/hw/vfio-user/device.c
@@ -293,7 +293,10 @@ static int vfio_user_device_io_set_irqs(VFIODevice *vbasedev,
      * Handle simple case
      */
     if ((irq->flags & VFIO_IRQ_SET_DATA_EVENTFD) == 0) {
-        size = sizeof(VFIOUserHdr) + irq->argsz;
+        if (__builtin_add_overflow(irq->argsz, sizeof(VFIOUserHdr), &size)) {
+            error_printf("vfio_user_set_irqs argsz too large\n");
+            return -E2BIG;
+        }
         msgp = g_malloc0(size);

         vfio_user_request_msg(&msgp->hdr, VFIO_USER_DEVICE_SET_IRQS, size, 0);