qc_usb_audio_probe() overwrites the return value of qmi_handle_init() with that of qmi_add_server() without checking it. When qmi_handle_init() fails, it has already freed the receive buffer and destroyed the workqueue, and qmi->sock may hold an error pointer. If QRTR is not available, qmi_handle_init() returns -EPROBE_DEFER and qmi->sock is ERR_PTR(-EAFNOSUPPORT), so qmi_add_server() passes it to kernel_sendmsg(): BUG: unable to handle page fault for address: ffffffffffffffb7 RIP: 0010:selinux_socket_sendmsg+0xa0/0x590 Call Trace: security_socket_sendmsg+0x29/0x50 __sock_sendmsg+0x43/0x150 kernel_sendmsg+0xd6/0x180 qmi_send_new_server+0x1b8/0x2b0 qmi_add_server+0x165/0x200 qc_usb_audio_probe+0xf4/0x2e0 really_probe+0x2b4/0x850 Had the probe gone on, the error and remove paths would call qmi_handle_release() on the half-initialized handle, which destroys the workqueue and frees the receive buffer a second time. Return the error from qmi_handle_init(), so that -EPROBE_DEFER defers the probe, and check qmi_add_server() as well. The bug was found with kbound, a static analysis prototype for ownership mismatches at kernel interfaces, on v7.2.12; it is present in mainline. Build-tested with x86_64 and arm64 allmodconfig (W=1, sparse): no new warnings. Run-tested on QEMU (x86_64, KVM) with KASAN and kmemleak, with the driver built in and a test module that registers the q6usb.qc-usb-audio-offload auxiliary device. Without QRTR, the probe crashes as above without this patch; with it the device is deferred and removing it again reports nothing. With QRTR the probe succeeds, and removal reports nothing either. Fixes: 326bbc348298 ("ALSA: usb-audio: qcom: Introduce QC USB SND offloading support") Cc: stable@vger.kernel.org Signed-off-by: Yuqiang Sun --- Notes: The bug was found with kbound, a research static analysis prototype. The patch, the changelog and the test setup were written with the help of an AI coding assistant (Claude); I have reviewed and tested them as described above. The runs were on mainline d135ab453a74; the code this patch touches is the same there and in sound for-linus, which it is based on. sound/usb/qcom/qc_audio_offload.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/sound/usb/qcom/qc_audio_offload.c b/sound/usb/qcom/qc_audio_offload.c index e4bfd43a2488..5ee568e0454c 100644 --- a/sound/usb/qcom/qc_audio_offload.c +++ b/sound/usb/qcom/qc_audio_offload.c @@ -1969,8 +1969,13 @@ static int qc_usb_audio_probe(struct auxiliary_device *auxdev, QMI_UAUDIO_STREAM_REQ_MSG_V01_MAX_MSG_LEN, &uaudio_svc_ops_options, &uaudio_stream_req_handlers); + if (ret) + goto free_qmi_hdl; + ret = qmi_add_server(svc->uaudio_svc_hdl, UAUDIO_STREAM_SERVICE_ID_V01, UAUDIO_STREAM_SERVICE_VERS_V01, 0); + if (ret) + goto release_qmi_hdl; uaudio_svc = svc; @@ -1987,7 +1992,9 @@ static int qc_usb_audio_probe(struct auxiliary_device *auxdev, release_qmi: qc_usb_audio_cleanup_qmi_dev(); +release_qmi_hdl: qmi_handle_release(svc->uaudio_svc_hdl); +free_qmi_hdl: kfree(svc->uaudio_svc_hdl); free_svc: kfree(svc); base-commit: 56abaa599bbbee5500e166ddb0b5241a00c1f763 -- 2.53.0