CVE-2021-47068

In the Linux kernel, the following vulnerability has been resolved:
net/nfc: fix use-after-free llcp_sock_bind/connect Commits 8a4cd82d (“nfc:
fix refcount leak in llcp_sock_connect()”) and c33b1cc62 (“nfc: fix
refcount leak in llcp_sock_bind()”) fixed a refcount leak bug in
bind/connect but introduced a use-after-free if the same local is assigned
to 2 different sockets. This can be triggered by the following simple
program: int sock1 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP ); int
sock2 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP ); memset( &addr,
0, sizeof(struct sockaddr_nfc_llcp) ); addr.sa_family = AF_NFC;
addr.nfc_protocol = NFC_PROTO_NFC_DEP; bind( sock1, (struct sockaddr*)
&addr, sizeof(struct sockaddr_nfc_llcp) ) bind( sock2, (struct sockaddr*)
&addr, sizeof(struct sockaddr_nfc_llcp) ) close(sock1); close(sock2); Fix
this by assigning NULL to llcp_sock->local after calling
nfc_llcp_local_put. This addresses CVE-2021-23134.