[PATCH 6.1 51/55] net: qualcomm: qca_uart: report the consumed byte on RX skb allocation failure

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Pengpeng Hou <pengpeng@iscas.ac.cn>

commit b76254c55dc8f23edc089027dd3f8792554c69fb upstream.

qca_tty_receive() consumes each input byte before checking whether a
completed frame needs a fresh receive skb. When the current byte completes
a frame, the driver delivers that frame and then allocates a new skb for
the next one.

If that allocation fails, the current code returns i even though data[i]
has already been consumed and may already have completed the delivered
frame. Since serdev interprets the return value as the number of accepted
bytes, this under-reports progress by one byte and can replay the final
byte of the completed frame into a fresh parser state on the next call.

Return i + 1 in that failure path so the accepted-byte count matches the
actual receive-state progress.

Fixes: dfc768fbe618 ("net: qualcomm: add QCA7000 UART driver")
Cc: stable@vger.kernel.org
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260402071207.4036-1-pengpeng@iscas.ac.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/qualcomm/qca_uart.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/qualcomm/qca_uart.c
+++ b/drivers/net/ethernet/qualcomm/qca_uart.c
@@ -115,7 +115,7 @@ qca_tty_receive(struct serdev_device *se
 			if (!qca->rx_skb) {
 				netdev_dbg(netdev, "recv: out of RX resources\n");
 				n_stats->rx_errors++;
-				return i;
+				return i + 1;
 			}
 		}
 	}