diff mbox series

[bpf-next,v1,2/4] bpf, sockmap: fix duplicated data transmission

Message ID 20250407142234.47591-3-jiayuan.chen@linux.dev
State New
Headers show
Series bpf, sockmap: Fix data loss and panic issues | expand

Commit Message

Jiayuan Chen April 7, 2025, 2:21 p.m. UTC 
In the !ingress path under sk_psock_handle_skb(), when sending data to the
remote under snd_buf limitations, partial skb data might be transmitted.

Although we preserved the partial transmission state (offset/length), the
state wasn't properly consumed during retries. This caused the retry path
to resend the entire skb data instead of continuing from the previous
offset, resulting in data overlap at the receiver side.

Fixes: 405df89dd52c ("bpf, sockmap: Improved check for empty queue")
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
---
 net/core/skmsg.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index 29cb5ffd56c0..9533b3e40ad7 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -656,11 +656,6 @@  static void sk_psock_backlog(struct work_struct *work)
 	int ret;
 
 	mutex_lock(&psock->work_mutex);
-	if (unlikely(state->len)) {
-		len = state->len;
-		off = state->off;
-	}
-
 	while ((skb = skb_peek(&psock->ingress_skb))) {
 		len = skb->len;
 		off = 0;
@@ -670,6 +665,13 @@  static void sk_psock_backlog(struct work_struct *work)
 			off = stm->offset;
 			len = stm->full_len;
 		}
+
+		/* Resume processing from previous partial state */
+		if (unlikely(state->len)) {
+			len = state->len;
+			off = state->off;
+		}
+
 		ingress = skb_bpf_ingress(skb);
 		skb_bpf_redirect_clear(skb);
 		do {
@@ -698,6 +700,8 @@  static void sk_psock_backlog(struct work_struct *work)
 			len -= ret;
 		} while (len);
 
+		/* The entire skb sent, clear state */
+		sk_psock_skb_state(psock, state, 0, 0);
 		skb = skb_dequeue(&psock->ingress_skb);
 		kfree_skb(skb);
 	}