During tls_sw_sendmsg_locked, we pre-allocate the encrypted message for the size we're expecting to send during the current iteration, but we may end up sending less, for example when splicing: if we're getting the data from small fragments of memory, we may fill up all the slots in the skmsg with less data than expected. In this case, we need to trim the encrypted message to only the length we actually need, to avoid pushing uninitialized bytes down the underlying TCP socket. Fixes: fe1e81d4f73b ("tls/sw: Support MSG_SPLICE_PAGES") Reported-by: Jann Horn Signed-off-by: Sabrina Dubroca --- net/tls/tls_sw.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index daac9fd4be7e..36ca3011ab87 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -1112,8 +1112,11 @@ static int tls_sw_sendmsg_locked(struct sock *sk, struct msghdr *msg, goto send_end; tls_ctx->pending_open_record_frags = true; - if (sk_msg_full(msg_pl)) + if (sk_msg_full(msg_pl)) { full_record = true; + sk_msg_trim(sk, msg_en, + msg_pl->sg.size + prot->overhead_size); + } if (full_record || eor) goto copied; -- 2.51.0