diff options
| author | Kuen-Han Tsai <khtsai@google.com> | 2025-06-17 13:07:11 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-07-17 18:37:12 +0200 |
| commit | 9e4af87bd08de65a549019b1496faa0f13a51df4 (patch) | |
| tree | 7c66db452ee93399641880c992c89bb95441a145 | |
| parent | abf3620cba68e0e51e5c21054ce4f925f75b3661 (diff) | |
Revert "usb: gadget: u_serial: Add null pointer check in gs_start_io"
commit f6c7bc4a6823a0a959f40866a1efe99bd03c2c5b upstream.
This reverts commit ffd603f214237e250271162a5b325c6199a65382.
Commit ffd603f21423 ("usb: gadget: u_serial: Add null pointer check in
gs_start_io") adds null pointer checks at the beginning of the
gs_start_io() function to prevent a null pointer dereference. However,
these checks are redundant because the function's comment already
requires callers to hold the port_lock and ensure port.tty and port_usb
are not null. All existing callers already follow these rules.
The true cause of the null pointer dereference is a race condition. When
gs_start_io() calls either gs_start_rx() or gs_start_tx(), the port_lock
is temporarily released for usb_ep_queue(). This allows port.tty and
port_usb to be cleared.
Fixes: ffd603f21423 ("usb: gadget: u_serial: Add null pointer check in gs_start_io")
Cc: stable <stable@kernel.org>
Signed-off-by: Kuen-Han Tsai <khtsai@google.com>
Reviewed-by: Prashanth K <prashanth.k@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20250617050844.1848232-1-khtsai@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/gadget/function/u_serial.c | 6 |
1 files changed, 1 insertions, 5 deletions
diff --git a/drivers/usb/gadget/function/u_serial.c b/drivers/usb/gadget/function/u_serial.c index 0a21c3ae02cc..2412f81f4412 100644 --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -543,20 +543,16 @@ static int gs_alloc_requests(struct usb_ep *ep, struct list_head *head, static int gs_start_io(struct gs_port *port) { struct list_head *head = &port->read_pool; - struct usb_ep *ep; + struct usb_ep *ep = port->port_usb->out; int status; unsigned started; - if (!port->port_usb || !port->port.tty) - return -EIO; - /* Allocate RX and TX I/O buffers. We can't easily do this much * earlier (with GFP_KERNEL) because the requests are coupled to * endpoints, as are the packet sizes we'll be using. Different * configurations may use different endpoints with a given port; * and high speed vs full speed changes packet sizes too. */ - ep = port->port_usb->out; status = gs_alloc_requests(ep, head, gs_read_complete, &port->read_allocated); if (status) |