[Qemu-devel] [PATCH v6 1/3] vhost: remove assertion to prevent crash

[Jay Zhou]

QEMU will assert on vhost-user backed virtio device hotplug if QEMU is
using more RAM regions than VHOST_MEMORY_MAX_NREGIONS (for example if
it were started with a lot of DIMM devices).

Fix it by returning error instead of asserting and let callers of
vhost_set_mem_table() handle error condition gracefully.

Cc: address@hidden
Signed-off-by: Igor Mammedov <address@hidden>
Signed-off-by: Jay Zhou <address@hidden>
---
 hw/virtio/vhost-user.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 093675e..8500562 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -317,11 +317,14 @@ static int vhost_user_set_mem_table(struct vhost_dev *dev,
                                      &offset);
         fd = memory_region_get_fd(mr);
         if (fd > 0) {
+            if (fd_num == VHOST_MEMORY_MAX_NREGIONS) {
+                error_report("Failed preparing vhost-user memory table msg");
+                return -1;
+            }
             msg.payload.memory.regions[fd_num].userspace_addr = 
reg->userspace_addr;
             msg.payload.memory.regions[fd_num].memory_size  = reg->memory_size;
             msg.payload.memory.regions[fd_num].guest_phys_addr = 
reg->guest_phys_addr;
             msg.payload.memory.regions[fd_num].mmap_offset = offset;
-            assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
             fds[fd_num++] = fd;
         }
     }
-- 
1.8.3.1