CVE-2017-1000112

Linux kernel: Exploitable memory corruption due to UFO to non-UFO path switch. When building a UFO packet with MSG_MORE __ip_append_data() calls ip_ufo_append_data() to append. However in between two send() calls, the append path can be switched from UFO to non-UFO one, which leads to a memory corruption. In case UFO packet lengths exceeds MTU, copy = maxfraglen - skb->len becomes negative on the non-UFO path and the branch to allocate new skb is taken. This triggers fragmentation and computation of fraggap = skb_prev->len - maxfraglen. Fraggap can exceed MTU, causing copy = datalen - transhdrlen - fraggap to become negative. Subsequently skb_copy_and_csum_bits() writes out-of-bounds. A similar issue is present in IPv6 code. The bug was introduced in e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach") on Oct 18 2005.

Linux kernel: Exploitable memory corruption due to UFO to non-UFO path switch. When building a UFO packet with MSG_MORE __ip_append_data() calls ip_ufo_append_data() to append. However in between two send() calls, the append path can be switched from UFO to non-UFO one, which leads to a memory corruption. In case UFO packet lengths exceeds MTU, copy = maxfraglen - skb->len becomes negative on the non-UFO path and the branch to allocate new skb is taken. This triggers fragmentation and computation of fraggap = skb_prev->len - maxfraglen. Fraggap can exceed MTU, causing copy = datalen - transhdrlen - fraggap to become negative. Subsequently skb_copy_and_csum_bits() writes out-of-bounds. A similar issue is present in IPv6 code. The bug was introduced in e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach") on Oct 18 2005.

Linux kernel: Existe una corrupción de memoria explotable debida al cambio de ruta de UFO a no UFO. Al crear un paquete UFO con MSG_MORE, __ip_append_data() llama a ip_ufo_append_data() para que se anexe. Sin embargo, entre dos llamadas send(), la ruta anexa puede cambiarse de UFO a no UFO, lo que lleva a una corrupción de memoria. Si la longitud del paquete UFO sobrepasa el MTU, copy = maxfraglen - skb->len se convierte en negativo en la ruta no UFO y se toma una rama para asignar un nuevo skb. Esto desencadena la fragmentación y el cálculo de fraggap = skb_prev->len - maxfraglen. fraggap puede exceder el MTU, lo que provoca que copy = datalen - transhdrlen - fraggap se vuelva negativo. En consecuencia, skb_copy_and_csum_bits() escribe fuera de límites. Existe un problema similar en el código IPv6. Este error fue introducido en e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach") el 18 de octubre de 2005.