CVE-2026-80982net/smc: fix use-after-free in smc_rx_pipe_buf_release()

Official description

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix use-after-free in smc_rx_pipe_buf_release() smc_rx_splice() hands RMB pages to a pipe and takes a socket reference per entry so the smc_sock stays alive until the reader finishes. The connection does not: a concurrent close runs smc_conn_free(), which releases the receive buffer back to the link group pool. smc_rx_pipe_buf_release() tests sk_state before taking the socket lock. The state can change between the test and the lock, and smc_rx_update_cons() then dereferences conn->rmb_desc and walks conn->lgr, which smc_conn_free() has already released. On the is_reg_err path smcr_buf_unuse() frees the descriptor outright, so this is a use-after-free. Take the socket lock first and test conn->freed instead. smc_conn_free() sets that flag before releasing anything, and every caller holds the socket lock. The two paths exclude each other: either the pipe release runs first with everything valid, or it sees the flag and skips the update.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/dadd97c8296b23aa816e91ed70041820ae087baa
• https://git.kernel.org/stable/c/df441f3efbb50eb0f120b8de4bf441c31fb0551d
• https://git.kernel.org/stable/c/6a644a7340df978785f3109d1e0726a982ce2c6f
• https://git.kernel.org/stable/c/0761e49aa78c2f1362511054c6e9670653858837
• https://git.kernel.org/stable/c/0926f59ca0f94120895b92180c636a48d0ed3a6d
• https://git.kernel.org/stable/c/c924884743e948e25625b7fbf3ee2a9325a204a7