CVE-2023-53296

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> sctp: check send stream number after wait_for_sndbuf<br /> <br /> This patch fixes a corner case where the asoc out stream count may change<br /> after wait_for_sndbuf.<br /> <br /> When the main thread in the client starts a connection, if its out stream<br /> count is set to N while the in stream count in the server is set to N - 2,<br /> another thread in the client keeps sending the msgs with stream number<br /> N - 1, and waits for sndbuf before processing INIT_ACK.<br /> <br /> However, after processing INIT_ACK, the out stream count in the client is<br /> shrunk to N - 2, the same to the in stream count in the server. The crash<br /> occurs when the thread waiting for sndbuf is awake and sends the msg in a<br /> non-existing stream(N - 1), the call trace is as below:<br /> <br /> KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]<br /> Call Trace:<br /> <br /> sctp_cmd_send_msg net/sctp/sm_sideeffect.c:1114 [inline]<br /> sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1777 [inline]<br /> sctp_side_effects net/sctp/sm_sideeffect.c:1199 [inline]<br /> sctp_do_sm+0x197d/0x5310 net/sctp/sm_sideeffect.c:1170<br /> sctp_primitive_SEND+0x9f/0xc0 net/sctp/primitive.c:163<br /> sctp_sendmsg_to_asoc+0x10eb/0x1a30 net/sctp/socket.c:1868<br /> sctp_sendmsg+0x8d4/0x1d90 net/sctp/socket.c:2026<br /> inet_sendmsg+0x9d/0xe0 net/ipv4/af_inet.c:825<br /> sock_sendmsg_nosec net/socket.c:722 [inline]<br /> sock_sendmsg+0xde/0x190 net/socket.c:745<br /> <br /> The fix is to add an unlikely check for the send stream number after the<br /> thread wakes up from the wait_for_sndbuf.