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.

• linux linux kernel (>= 4.4.267 < 4.4.269) • linux linux kernel (>= 4.9.267 < 4.9.269) • linux linux kernel (>= 4.14.231 < 4.14.233) • linux linux kernel (>= 4.19.187 < 4.19.191) • linux linux kernel (>= 5.4.112 < 5.4.119) • linux linux kernel (>= 5.10.30 < 5.10.37) • linux linux kernel (>= 5.11.14 < 5.11.21) • linux linux kernel (>= 5.12 < 5.12.4)