net/tls: Fail tls_sw_splice_read() after a failed async decrypt

net/tls: Fail tls_sw_splice_read() after a failed async decrypt

When an async decrypt fails, tls_decrypt_done() records the error in
ctx->async_wait.err and calls tls_err_abort(), which stores it in
sk_err. tls_sw_recvmsg() and tls_sw_read_sock() each read
async_wait.err once they hold the reader lock and fail the call: a
record that did not authenticate breaks the connection.

tls_sw_splice_read() has no such check, and sk_err does not stand in
for one. tls_rx_rec_wait() tests sk_err only inside the loop it
skips whenever a record is already parsed, and the first reader to
reach sock_error() clears it, while async_wait.err persists. A
splice therefore keeps delivering records on a connection that
recvmsg() and read_sock() refuse to read.

Read async_wait.err in tls_sw_splice_read() as the other two readers
do.

Fixes: f314bfee81b1 ("tls: rx: return the already-copied data on crypto error")
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Chuck Lever <cel@kernel.org>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://patch.msgid.link/20260806-tls-splice-crypto-fix-v1-1-a2624005a286@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>