CVE-2021-47244: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47244 affects the Linux kernel's TCP option parser in the MPTCP (Multipath TCP) implementation. The vulnerability was discovered in the mptcp_get_options function where it could read one byte out of bounds when parsing TCP options. This occurs when the length is 1 and the opcode is neither TCPOPT_EOL nor TCPOPT_NOP, causing it to read an additional byte beyond the length boundary (Kernel Commit).

The vulnerability exists in the net/mptcp/options.c file where the TCP option parser could perform an out-of-bounds read. When processing TCP options with a length of 1, the parser reads the opcode byte and then attempts to read another byte for non-EOL/NOP options, exceeding the specified length. This issue was fixed by adding a length check before reading the option size (Kernel Commit).

The vulnerability could lead to an out-of-bounds read in the kernel's memory space, potentially causing information disclosure or system crashes. The issue affects systems running Linux kernel versions that include the vulnerable MPTCP implementation (Kernel Commit).

The vulnerability was fixed by adding a proper length check before reading the option size. The fix was implemented in the Linux kernel through a patch that adds a condition to verify if the length is less than 2 before attempting to read the option size (Kernel Commit).