[Qemu-devel] [PATCH v2 0/2] Avoid sending zero-size packets

[Oleinik, Alexander]

While fuzzing the virtio-net tx vq, I ran into an assertion failure due
to iov_copy offsets larger than the total iov size. Though there is
a check to cover this, it does not execute when !n->has_vnet_hdr. This
patch tries to fix this. 
The call stack for the assertion failure:

#8 in __assert_fail (libc.so.6+0x300f1)
#9 in iov_copy iov.c:266:5
#10 in virtio_net_flush_tx virtio-net.c:2073:23
#11 in virtio_net_tx_bh virtio-net.c:2197:11
#12 in aio_bh_poll async.c:118:13
#13 in aio_dispatch aio-posix.c:460:5
#14 in aio_ctx_dispatch async.c:261:5
#15 in g_main_context_dispatch (libglib-2.0.so.0+0x4df2d)
#16 in glib_pollfds_poll main-loop.c:213:9
#17 in os_host_main_loop_wait main-loop.c:236
#18 in main_loop_wait main-loop.c:512
#19 in virtio_net_tx_fuzz virtio-net-fuzz.c:160:3

v2: add details to  comment for the change to qemu_sendv_packet_async

Alexander Oleinik (2):
  net: assert that tx packets have nonzero size
  virtio-net: check that tx packet has positive size

 hw/net/virtio-net.c | 15 +++++++++------
 net/net.c           |  9 +++++++++
 2 files changed, 18 insertions(+), 6 deletions(-)

-- 
2.20.1