ktls, sockmap: Fix missing uncharge operation

[ Upstream commit 79f0c39ae7d3dc628c01b02f23ca5d01f9875040 ]

When we specify apply_bytes, we divide the msg into multiple segments,
each with a length of 'send', and every time we send this part of the data
using tcp_bpf_sendmsg_redir(), we use sk_msg_return_zero() to uncharge the
memory of the specified 'send' size.

However, if the first segment of data fails to send, for example, the
peer's buffer is full, we need to release all of the msg. When releasing
the msg, we haven't uncharged the memory of the subsequent segments.

This modification does not make significant logical changes, but only
fills in the missing uncharge places.

This issue has existed all along, until it was exposed after we added the
apply test in test_sockmap:
commit 3448ad23b34e ("selftests/bpf: Add apply_bytes test to test_txmsg_redir_wait_sndmem in test_sockmap")

Fixes: d3b18ad31f93 ("tls: add bpf support to sk_msg handling")
Reported-by: Cong Wang <xiyou.wangcong@gmail.com>
Closes: https://lore.kernel.org/bpf/aAmIi0vlycHtbXeb@pop-os.localdomain/T/#t
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Link: https://lore.kernel.org/r/20250425060015.6968-2-jiayuan.chen@linux.dev
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index af820ae9b1a52270a89379990c07bd99e6829dfc..5f95f837dfc7fd17a39068c89d0c3aaf418436ad 100644 (file)
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -904,6 +904,13 @@ more_data:
                                            &msg_redir, send, flags);
                lock_sock(sk);
                if (err < 0) {
+                       /* Regardless of whether the data represented by
+                        * msg_redir is sent successfully, we have already
+                        * uncharged it via sk_msg_return_zero(). The
+                        * msg->sg.size represents the remaining unprocessed
+                        * data, which needs to be uncharged here.
+                        */
+                       sk_mem_uncharge(sk, msg->sg.size);
                        *copied -= sk_msg_free_nocharge(sk, &msg_redir);
                        msg->sg.size = 0;
                }