CVE-2026-80979net/smc: unregister the connection before draining the rx tasklet

Official description

In the Linux kernel, the following vulnerability has been resolved: net/smc: unregister the connection before draining the rx tasklet smc_conn_free() calls smc_ism_unset_conn() only while the link group is still on its device list, and never sets conn->killed. smc_lgr_terminate_sched() unlinks the group immediately and defers killing its connections to a work item, so a connection freed in that window keeps its smcd->conn[] slot with both gates in smcd_handle_irq() open, and the device can re-arm the receive tasklet after tasklet_kill() has returned. On the DMB-nocopy path the ghost send buffer is freed right after that drain, so the re-armed tasklet dereferences it. Unregister unconditionally and drain before the detach at both teardown sites, mirroring rmb_desc, which smc_buf_unuse() releases after the drain. Clear conn->sndbuf_desc before freeing it as well, so a reader that samples the pointer cannot get one that is already freed.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/b6b6ac713ee82b340a8e3be30b101bd2840deec4
• https://git.kernel.org/stable/c/b4d540ac95cd35c6ebab6afb7eae2bcac7b277a5
• https://git.kernel.org/stable/c/5bd8b764a610b6b6bc0c4d3d01652747f6e0b5c3
• https://git.kernel.org/stable/c/b74d313567dfc1b7e56629ddbad04e728686f235
• https://git.kernel.org/stable/c/36cdf5d48ca191dcd71c28cadbe0981b1d25318d