On Thu, Oct 23, 2025 at 12:08 AM Bui Quang Minh minhquangbui99@gmail.com wrote:
Since commit 4959aebba8c0 ("virtio-net: use mtu size as buffer length for big packets"), when guest gso is off, the allocated size for big packets is not MAX_SKB_FRAGS * PAGE_SIZE anymore but depends on negotiated MTU. The number of allocated frags for big packets is stored in vi->big_packets_num_skbfrags.
Because the host announced buffer length can be malicious (e.g. the host vhost_net driver's get_rx_bufs is modified to announce incorrect length), we need a check in virtio_net receive path. Currently, the check is not adapted to the new change which can lead to NULL page pointer dereference in the below while loop when receiving length that is larger than the allocated one.
This commit fixes the received length check corresponding to the new change.
Fixes: 4959aebba8c0 ("virtio-net: use mtu size as buffer length for big packets") Cc: stable@vger.kernel.org Signed-off-by: Bui Quang Minh minhquangbui99@gmail.com
Changes in v4:
- Remove unrelated changes, add more comments
Changes in v3:
- Convert BUG_ON to WARN_ON_ONCE
Changes in v2:
- Remove incorrect give_pages call
Acked-by: Jason Wang jasowang@redhat.com
Thanks