[PATCH 6.19 306/311] usb: gadget: f_uac1_legacy: validate control request size

Greg Kroah-Hartman
2026-04-08T19:02:57Z

From: Taegu Ha <hataegu0826@gmail.com>

commit 6e0e34d85cd46ceb37d16054e97a373a32770f6c upstream.

f_audio_complete() copies req->length bytes into a 4-byte stack
variable:

u32 data = 0;
memcpy(&data, req->buf, req->length);

req->length is derived from the host-controlled USB request path,
which can lead to a stack out-of-bounds write.

Validate req->actual against the expected payload size for the
supported control selectors and decode only the expected amount
of data.

This avoids copying a host-influenced length into a fixed-size
stack object.

Signed-off-by: Taegu Ha <hataegu0826@gmail.com>
Cc: stable <stable@kernel.org>
Link: https://patch.msgid.link/20260401191311.3604898-1-hataegu0826@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/gadget/function/f_uac1_legacy.c | 47 ++++++++++++++++++++++------
1 file changed, 37 insertions(+), 10 deletions(-)

--- a/drivers/usb/gadget/function/f_uac1_legacy.c
+++ b/drivers/usb/gadget/function/f_uac1_legacy.c
@@ -360,19 +360,46 @@ static int f_audio_out_ep_complete(struc
static void f_audio_complete(struct usb_ep *ep, struct usb_request *req)
{
struct f_audio *audio = req->context;
- int status = req->status;
- u32 data = 0;
struct usb_ep *out_ep = audio->out_ep;

- switch (status) {
-
- case 0: /* normal completion? */
- if (ep == out_ep)
+ switch (req->status) {
+ case 0:
+ if (ep == out_ep) {
f_audio_out_ep_complete(ep, req);
- else if (audio->set_con) {
- memcpy(&data, req->buf, req->length);
- audio->set_con->set(audio->set_con, audio->set_cmd,
- le16_to_cpu(data));
+ } else if (audio->set_con) {
+ struct usb_audio_control *con = audio->set_con;
+ u8 type = con->type;
+ u32 data;
+ bool valid_request = false;
+
+ switch (type) {
+ case UAC_FU_MUTE: {
+ u8 value;
+
+ if (req->actual == sizeof(value)) {
+ memcpy(&value, req->buf, sizeof(value));
+ data = value;
+ valid_request = true;
+ }
+ break;
+ }
+ case UAC_FU_VOLUME: {
+ __le16 value;
+
+ if (req->actual == sizeof(value)) {
+ memcpy(&value, req->buf, sizeof(value));
+ data = le16_to_cpu(value);
+ valid_request = true;
+ }
+ break;
+ }
+ }
+
+ if (valid_request)
+ con->set(con, audio->set_cmd, data);
+ else
+ usb_ep_set_halt(ep);
+
audio->set_con = NULL;
}
break;