From: Akihiko Odaki Date: Fri, 22 Nov 2024 05:03:08 +0000 (+0900) Subject: virtio-net: Fix size check in dhclient workaround X-Git-Tag: v7.2.16~29 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=acb39d8e6e4a9b76d991d0be9d9d9a9e43644902;p=thirdparty%2Fqemu.git virtio-net: Fix size check in dhclient workaround work_around_broken_dhclient() accesses IP and UDP headers to detect relevant packets and to calculate checksums, but it didn't check if the packet has size sufficient to accommodate them, causing out-of-bound access hazards. Fix this by correcting the size requirement. Fixes: 1d41b0c1ec66 ("Work around dhclient brokenness") Cc: qemu-stable@nongnu.org Signed-off-by: Akihiko Odaki Signed-off-by: Jason Wang (cherry picked from commit a8575f7fb2f213e6690b23160b04271d47fdfaa8) Signed-off-by: Michael Tokarev --- diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 925a5c319e7..204a80ec711 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -1647,8 +1647,11 @@ static void virtio_net_hdr_swap(VirtIODevice *vdev, struct virtio_net_hdr *hdr) static void work_around_broken_dhclient(struct virtio_net_hdr *hdr, uint8_t *buf, size_t size) { + size_t csum_size = ETH_HLEN + sizeof(struct ip_header) + + sizeof(struct udp_header); + if ((hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && /* missing csum */ - (size > 27 && size < 1500) && /* normal sized MTU */ + (size >= csum_size && size < 1500) && /* normal sized MTU */ (buf[12] == 0x08 && buf[13] == 0x00) && /* ethertype == IPv4 */ (buf[23] == 17) && /* ip.protocol == UDP */ (buf[34] == 0 && buf[35] == 67)) { /* udp.srcport == bootps */