6.1-stable review patch. If anyone has any objections, please let me know.
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From: Jiayuan Chen jiayuan.chen@linux.dev
[ Upstream commit 3b4f14b794287be137ea2c6158765d1ea1e018a4 ]
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 Link: https://lore.kernel.org/r/20250407142234.47591-3-jiayuan.chen@linux.dev Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/skmsg.c | 14 +++++++++----- 1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/net/core/skmsg.c b/net/core/skmsg.c index 5a790cd1121b1..72f4949cbb70f 100644 --- a/net/core/skmsg.c +++ b/net/core/skmsg.c @@ -654,11 +654,6 @@ 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; @@ -668,6 +663,13 @@ 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 { @@ -695,6 +697,8 @@ 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); }