CVE-2021-47243

In the Linux kernel, the following vulnerability has been resolved:
sch_cake: Fix out of bounds when parsing TCP options and header The TCP
option parser in cake qdisc (cake_get_tcpopt and cake_tcph_may_drop) 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 doff
validation in cake_get_tcphdr to avoid parsing garbage as TCP header.
Although it wasn’t strictly an out-of-bounds access (memory was allocated),
garbage values could be read where CAKE expected the TCP header if doff was
smaller than 5.