tree 493b28e33fd353de5875c9f48faab0b6a6452c1f
parent 5e16a190b6fffa67edfa8fbee7f62186572e2bf1
author Jakub Kicinski <kuba@kernel.org> 1755656391 -0700
committer Robert Kolchmeyer <rkolchmeyer@google.com> 1756243595 -0700

tls: fix handling of zero-length records on the rx_list

commit 62708b9452f8eb77513115b17c4f8d1a22ebf843 upstream.

Each recvmsg() call must process either
 - only contiguous DATA records (any number of them)
 - one non-DATA record

If the next record has different type than what has already been
processed we break out of the main processing loop. If the record
has already been decrypted (which may be the case for TLS 1.3 where
we don't know type until decryption) we queue the pending record
to the rx_list. Next recvmsg() will pick it up from there.

Queuing the skb to rx_list after zero-copy decrypt is not possible,
since in that case we decrypted directly to the user space buffer,
and we don't have an skb to queue (darg.skb points to the ciphertext
skb for access to metadata like length).

Only data records are allowed zero-copy, and we break the processing
loop after each non-data record. So we should never zero-copy and
then find out that the record type has changed. The corner case
we missed is when the initial record comes from rx_list, and it's
zero length.

BUG=b/440567550
TEST=presubmit
RELEASE_NOTE=Fixed KCTF-62708b9 in the Linux kernel.

Reported-by: Muhammad Alifa Ramdhan <ramdhan@starlabs.sg>
Reported-by: Billy Jheng Bing-Jhong <billy@starlabs.sg>
Fixes: 84c61fe1a75b ("tls: rx: do not use the standard strparser")
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://patch.msgid.link/20250820021952.143068-1-kuba@kernel.org
Change-Id: I3775cf972ab094b6082449d301c1b9c2d8da0181
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 767e0c9809b922f1388508e7f4a7551f68fe0547)
Signed-off-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/109885
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Kevin Berry <kpberry@google.com>