A flaw was found in the way the Linux kernel's networking subsystem handled offloaded packets with multiple layers of encapsulation in the GRO (Generic Receive Offload) code path. A remote attacker could use this flaw to trigger unbounded recursion in the kernel that could lead to stack corruption, resulting in a system crash.
Fixed by: https://git.kernel.org/linus/fac8e0f579695a3ecbc4d3cac369139d7f819971 (4.6)
Introduced by: htttps://git.kernel.org/linus/bf5a755f5e9186406bbf50f4087100af5bd68e40 (3.13)
4.4: Fixed since 4.4.29 (5699b3431e0b14736867484b8669ead2d40f575e)
There's currently some media attention regarding increased GRE traffic which could be related to the recent published advisories, see https://isc.sans.edu/forums/diary/Increase+in+Protocol+47+denys/21865/