7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bryam Vargas [ Upstream commit c0703534b223a5c6993e0f000fd1c3abe621fb65 ] When a send wraps the end of the send buffer, smc_tx_sendmsg() copies the data in two chunks. If memcpy_from_msg() faults on the second one, smc_tx_sendmsg() returns send_done, which already counts the first chunk, but leaves tx_curs_prep and sndbuf_space as they were. send() reports bytes the peer never receives, and the next send() overwrites them. Any caller can hit this on its own stream with a buffer whose tail is unreadable. On a fault in the second chunk, queue the first one. The next pass retries the rest and returns send_done if it faults again, so send() reports only what it queued, as TCP does. Fixes: e6727f39004b ("smc: send data (through RDMA)") Cc: stable@vger.kernel.org Signed-off-by: Bryam Vargas Link: https://patch.msgid.link/20261013-b4-disp-872a3689-v1-1-2a4c63b04761@proton.me Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/smc/smc_tx.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c index 3144b4b1fe290..495fb1354728c 100644 --- a/net/smc/smc_tx.c +++ b/net/smc/smc_tx.c @@ -249,6 +249,13 @@ int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len) rc = memcpy_from_msg(sndbuf_base + chunk_off, msg, chunk_len); if (rc) { + if (chunk) { + /* send_done counts the first chunk: + * queue it and retry the rest + */ + copylen -= chunk_len; + break; + } smc_sndbuf_sync_sg_for_device(conn); if (send_done) return send_done; -- 2.53.0