From 7b2f38b816fb7980badb69e3fcce6db14a8c0316 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Tue, 19 Aug 2025 19:19:51 -0700 Subject: [PATCH] UPSTREAM: 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: 440544511 Reported-by: Muhammad Alifa Ramdhan Reported-by: Billy Jheng Bing-Jhong Fixes: 84c61fe1a75b ("tls: rx: do not use the standard strparser") Reviewed-by: Sabrina Dubroca Link: https://patch.msgid.link/20250820021952.143068-1-kuba@kernel.org Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman (cherry picked from commit c09dd3773b5950e9cfb6c9b9a5f6e36d06c62677) Signed-off-by: Lee Jones Change-Id: I8c4c8db7d160497172be885ef5d82109b8e073ad --- net/tls/tls_sw.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c index 84d63fc7e36a..84c65e814dad 100644 --- a/net/tls/tls_sw.c +++ b/net/tls/tls_sw.c @@ -1761,6 +1761,9 @@ int decrypt_skb(struct sock *sk, struct scatterlist *sgout) return tls_decrypt_sg(sk, NULL, sgout, &darg); } +/* All records returned from a recvmsg() call must have the same type. + * 0 is not a valid content type. Use it as "no type reported, yet". + */ static int tls_record_content_type(struct msghdr *msg, struct tls_msg *tlm, u8 *control) { @@ -2004,8 +2007,10 @@ int tls_sw_recvmsg(struct sock *sk, if (err < 0) goto end; + /* process_rx_list() will set @control if it processed any records */ copied = err; - if (len <= copied || (copied && control != TLS_RECORD_TYPE_DATA) || rx_more) + if (len <= copied || rx_more || + (control && control != TLS_RECORD_TYPE_DATA)) goto end; target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);