[PATCH] mmc: sdio_uart: fix xmit_fifo leak when the port table is full

[PATCH] mmc: sdio_uart: fix xmit_fifo leak when the port table is full

[Felix Gu]

sdio_uart_add_port() allocates the transmit fifo before claiming a
slot in sdio_uart_table[].  When all UART_NR slots are taken, it
returns -EBUSY with the fifo still allocated, but the probe error
path only kfree()s the port, leaking the transmit fifo.

Free the fifo in the failure path of sdio_uart_add_port() itself so
the function retains nothing on error.

Fixes: 8b197a5ce7a7 ("sdio_uart: Use kfifo instead of the messy circ stuff")
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
---
 drivers/mmc/core/sdio_uart.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/mmc/core/sdio_uart.c b/drivers/mmc/core/sdio_uart.c
index 7fd5dedf3ac0..705163c42972 100644
--- a/drivers/mmc/core/sdio_uart.c
+++ b/drivers/mmc/core/sdio_uart.c
@@ -104,6 +104,9 @@ static int sdio_uart_add_port(struct sdio_uart_port *port)
 	}
 	spin_unlock(&sdio_uart_table_lock);
 
+	if (ret)
+		kfifo_free(&port->xmit_fifo);
+
 	return ret;
 }
 

---
base-commit: 903c1cf6dff9964e71eda98a39e2e5d442050472
change-id: 20260822-sdio_uart-a702d7cc5eb4

Best regards,
--  
Felix Gu <ustc.gu@gmail.com>

Re: [PATCH] mmc: sdio_uart: fix xmit_fifo leak when the port table is full

[Ulf Hansson]

On Fri, Aug 21, 2026 at 8:58 PM Felix Gu <ustc.gu@gmail.com> wrote:
>
> sdio_uart_add_port() allocates the transmit fifo before claiming a
> slot in sdio_uart_table[].  When all UART_NR slots are taken, it
> returns -EBUSY with the fifo still allocated, but the probe error
> path only kfree()s the port, leaking the transmit fifo.
>
> Free the fifo in the failure path of sdio_uart_add_port() itself so
> the function retains nothing on error.
>
> Fixes: 8b197a5ce7a7 ("sdio_uart: Use kfifo instead of the messy circ stuff")
> Signed-off-by: Felix Gu <ustc.gu@gmail.com>

Applied for fixes and by adding a stable tag, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/core/sdio_uart.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/mmc/core/sdio_uart.c b/drivers/mmc/core/sdio_uart.c
> index 7fd5dedf3ac0..705163c42972 100644
> --- a/drivers/mmc/core/sdio_uart.c
> +++ b/drivers/mmc/core/sdio_uart.c
> @@ -104,6 +104,9 @@ static int sdio_uart_add_port(struct sdio_uart_port *port)
>         }
>         spin_unlock(&sdio_uart_table_lock);
>
> +       if (ret)
> +               kfifo_free(&port->xmit_fifo);
> +
>         return ret;
>  }
>
>
> ---
> base-commit: 903c1cf6dff9964e71eda98a39e2e5d442050472
> change-id: 20260822-sdio_uart-a702d7cc5eb4
>
> Best regards,
> --
> Felix Gu <ustc.gu@gmail.com>
>