[PATCH 6.1 0447/1146] bpf, sockmap: Fix data loss caused by using apply_bytes on ingress redirect

Greg Kroah-Hartman
2022-12-28T15:57:44Z

From: Pengcheng Yang <yangpc@wangsu.com>

[ Upstream commit 9072931f020bfd907d6d89ee21ff1481cd78b407 ]

Use apply_bytes on ingress redirect, when apply_bytes is less than
the length of msg data, some data may be skipped and lost in
bpf_tcp_ingress().

If there is still data in the scatterlist that has not been consumed,
we cannot move the msg iter.

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/1669718441-2654-4-git-send-email-yangpc@wangsu.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/tcp_bpf.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 275c5ca9e04d..94aad3870c5f 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -45,8 +45,11 @@ static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
tmp->sg.end = i;
if (apply) {
apply_bytes -= size;
- if (!apply_bytes)
+ if (!apply_bytes) {
+ if (sge->length)
+ sk_msg_iter_var_prev(i);
break;
+ }
}
} while (i != msg->sg.end);

--
2.35.1