Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:  net/smc: avoid NULL deref of conn->lnk in smc_msg_event tracepoint  The smc_msg_event tracepoint class, shared by smc_tx_sendmsg and smc_rx_recvmsg, unconditionally dereferences smc->conn.lnk:  	__string(name, smc->conn.lnk->ibname)  conn->lnk is only set for SMC-R; for SMC-D it is NULL. Other code on these paths already handles this (e.g. !conn->lnk in SMC_STAT_RMB_TX_SIZE_SMALL()). With the tracepoint enabled, the first sendmsg()/recvmsg() on an SMC-D socket crashes:    Oops: general protection fault, probably for non-canonical address   KASAN: null-ptr-deref in range [...]   RIP: 0010:strlen+0x1e/0xa0   Call Trace:    trace_event_raw_event_smc_msg_event (net/smc/smc_tracepoint.h:44)    smc_rx_recvmsg (net/smc/smc_rx.c:515)    smc_recvmsg (net/smc/af_smc.c:2859)    __sys_recvfrom (net/socket.c:2315)    __x64_sys_recvfrom (net/socket.c:2326)    do_syscall_64  The faulting address 0x3e0 is offsetof(struct smc_link, ibname), confirming the NULL ->lnk deref. Enabling the tracepoint requires root, but the trigger itself is unprivileged: socket(AF_SMC, ...) has no capability check, and SMC-D negotiation needs no admin step on s390 or on x86 with the loopback ISM device loaded.  Log an empty device name for SMC-D instead of dereferencing NULL.