Re: [PATCH net-next v2 1/6] net/tls: Bound consecutive no-data records in tls_sw_read_sock()

On 7/20/26 4:27 PM, Chuck Lever wrote:

A record that delivers no payload -- an empty TLS 1.3 data record
today, a control record once read_sock_rectype() lands -- leaves
tls_sw_read_sock() in its loop without advancing the caller's read
descriptor. A peer that streams such records keeps the receive loop
running, and the socket lock held, for as long as the records
arrive.

Cap the number of consecutive no-data records consumed per call. The
count resets on any record that delivers bytes, so a normal stream
is unaffected; a peer supplying only empty records is bounded to
TLS_RX_NODATA_LIMIT iterations before the call returns 0. read_sock
consumers treat that as "no progress, re-poll" rather than EOF, so
the connection stays up and makes progress once real data arrives.

Only tls_sw_read_sock() needs this cap. Its consumers drive the receive
loop from kernel context -- a work item or service thread holding the
socket lock across the whole call with no return to userspace -- so an
unbounded empty-record stream keeps that context and the lock pinned
for as long as the flood lasts. The cap supplies the return boundary
that a system call would otherwise provide. tls_sw_splice_read()
and tls_sw_recvmsg() already have one: they run in the calling task's
context, reschedule while draining the socket backlog (cond_resched()
in __release_sock()), and drop the socket lock when the call returns. A
flood there costs the caller only its own scheduler time, so the cap
would add nothing.

Signed-off-by: Chuck Lever <cel@kernel.org>
---
  net/tls/tls_sw.c | 13 +++++++++++++
  1 file changed, 13 insertions(+)

This is technically a fix, so it might be worthwhile sending it
on its own.

Otherwise:

Reviewed-by: Hannes Reinecke <hare@kernel.org>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich