In the Linux kernel, the following vulnerability has been resolved:
mptcp: clear 'kern' flag from fallback sockets
The mptcp ULP extension relies on sk->sk_sock_kern being set correctly:
It prevents setsockopt(fd, IPPROTO_TCP, TCP_ULP, "mptcp", 6); from
working for plain tcp sockets (any userspace-exposed socket).
But in case of fallback, accept() can return a plain tcp sk.
In such case, sk is still tagged as 'kernel' and setsockopt will work.
This will crash the kernel, The subflow extension has a NULL ctx->conn
mptcp socket:
BUG: KASAN: null-ptr-deref in subflow_data_ready+0x181/0x2b0
Call Trace:
 tcp_data_ready+0xf8/0x370
 [..]
                
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Information
                Published : 2024-06-19 15:15
Updated : 2024-11-21 06:36
NVD link : CVE-2021-47593
Mitre link : CVE-2021-47593
CVE.ORG link : CVE-2021-47593
JSON object : View
Products Affected
                linux
- linux_kernel
 
CWE
                
                    
                        
                        CWE-476
                        
            NULL Pointer Dereference
