CVE-2021-47245 Information

Description

In the Linux kernel the following vulnerability has been resolved:

netfilter: synproxy: Fix out of bounds when parsing TCP options

The TCP option parser in synproxy (synproxy_parse_options) could read one byte out of bounds. When the length is 1 the execution flow gets into the loop reads one byte of the opcode and if the opcode is neither TCPOPT_EOL nor TCPOPT_NOP it reads one more byte which exceeds the length of 1.

This fix is inspired by commit 9609dad263f8 (\ipv4: tcp_input: fix stack out of bounds when parsing TCP options.).

v2 changes:

Added an early return when length < 0 to avoid calling skb_header_pointer with negative length.

Reference

https://git.kernel.org/stable/c/e1eb98cfeafdd85537e7e3cefe93ca9bfbcc3ea8 https://git.kernel.org/stable/c/576c1526b4d83c44ad7b673cb841f36cbc6cb6c4 https://git.kernel.org/stable/c/674b5f0c6a4fc5d3abce877048290cea6091fcb1 https://git.kernel.org/stable/c/7d9a9a1a88a3da574e019b4de756bc73337b3b0b https://git.kernel.org/stable/c/6defc77d48eff74075b80ad5925061b2fc010d98 https://git.kernel.org/stable/c/9cdf299ba4e153b5e56187648420de22c6216f02 https://git.kernel.org/stable/c/f648089337cb8ed40b2bb96e244f72b9d97dc96b https://git.kernel.org/stable/c/5fc177ab759418c9537433e63301096e733fb915