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

Summary

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.

Timeline

1. Sep 11, 2026, 7:42 PM UTCCVE published
2. Oct 19, 2026, 8:46 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 21f6f41e82e59740e26e06e77bdf58dc7f6f08dd · fixed in ab26e12dd5d2f43d939fcf456933a816e81d2e51; From ae2be35cbed2c8385e890147ea321a3fcc3ca5fa · fixed in e3fcff8d22a6c9540748846cd800443a643553a6; From ae2be35cbed2c8385e890147ea321a3fcc3ca5fa · fixed in f950e1b1f0aad334f9a9ee552c4dd5b794ebdd45; From ae2be35cbed2c8385e890147ea321a3fcc3ca5fa · fixed in f517cf02033801a28f98d86ca613a3533cf066b3; From ae2be35cbed2c8385e890147ea321a3fcc3ca5fa · fixed in b395dd319cea422239cb45b998fb38d7e373af87; From 6.6.66 · fixed in 6.6.157

• Linux Linux

  6.10

• KernelLinux

  fixed in 6.6.157; From 6.7.0 · fixed in 6.12.109; From 6.10.0 · fixed in 6.18.50; From 6.13.0 · fixed in 7.2.4

References 5