CVE-2026-80984net/smc: do not dereference an unset send buffer on the SMC-D teardown path

Official description

In the Linux kernel, the following vulnerability has been resolved: net/smc: do not dereference an unset send buffer on the SMC-D teardown path smc_close_stream_wait() calls smc_tx_prepared_sends() from inside its sk_wait_event() condition, and sk_wait_event() evaluates that condition once with the socket lock released. smcd_buf_detach() clears conn->sndbuf_desc from smc_conn_kill() under lock_sock(), so a link group terminating while a socket waits there leaves the helper dereferencing NULL, faulting out of close(). SIOCOUTQ reads the field by hand, and smc_close_cancel_work() drops the lock across two cancel_*_sync() calls. Sample the pointer once in the helper, report nothing prepared while it is unset, and bound the ioctl the same way. The receive tasklet dereferences the field directly in smc_cdc_msg_recv_action(), not through this helper; 1/2 is what keeps it from running that late.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/ab26e12dd5d2f43d939fcf456933a816e81d2e51
• https://git.kernel.org/stable/c/e3fcff8d22a6c9540748846cd800443a643553a6
• https://git.kernel.org/stable/c/f950e1b1f0aad334f9a9ee552c4dd5b794ebdd45
• https://git.kernel.org/stable/c/f517cf02033801a28f98d86ca613a3533cf066b3
• https://git.kernel.org/stable/c/b395dd319cea422239cb45b998fb38d7e373af87