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Tue, 9 Jan 2024 03:57:52 -0800 Message-ID: <5ef9db3d-1e60-4f42-8a5b-52a9800e4707@quicinc.com> Date: Tue, 9 Jan 2024 17:27:49 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] usb: core: Prevent null pointer dereference in update_port_device_state Content-Language: en-US To: Sergei Shtylyov , Greg Kroah-Hartman , Alan Stern CC: Krishna Kurapati , , , References: <20240109061708.26288-1-quic_ugoswami@quicinc.com> <3bb51617-81e1-7d19-598d-2b57164320e1@gmail.com> From: Udipto Goswami In-Reply-To: <3bb51617-81e1-7d19-598d-2b57164320e1@gmail.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: BtjOb8AzAwaf74a8g6BNVskhpdeZaDgv X-Proofpoint-ORIG-GUID: BtjOb8AzAwaf74a8g6BNVskhpdeZaDgv X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-09_01,2023-12-07_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 clxscore=1011 lowpriorityscore=0 suspectscore=0 malwarescore=0 adultscore=0 phishscore=0 impostorscore=0 mlxlogscore=949 spamscore=0 bulkscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2311290000 definitions=main-2401090097 Hi Sergei, On 1/9/2024 3:01 PM, Sergei Shtylyov wrote: > On 1/9/24 9:17 AM, Udipto Goswami wrote: > >> Currently,the function update_port_device_state gets the usb_hub from >> udev->parent by calling usb_hub_to_struct_hub. >> However, in case the actconfig or the maxchild is 0, the usb_hub would >> be NULL and upon further accessing to get port_dev would result in null >> pointer dereference. >> >> Fix this by introducing an if check after the usb_hub is populated. >> >> Fixes: 83cb2604f641 ("usb: core: add sysfs entry for usb device state") >> Cc: stable@vger.kernel.org >> Signed-off-by: Udipto Goswami >> --- >> v3: Re-wrote the comment for better context. >> v2: Introduced comment for the if check & CC'ed stable. >> >> drivers/usb/core/hub.c | 20 +++++++++++++++++--- >> 1 file changed, 17 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c >> index ffd7c99e24a3..6b514546e59b 100644 >> --- a/drivers/usb/core/hub.c >> +++ b/drivers/usb/core/hub.c >> @@ -2053,9 +2053,23 @@ static void update_port_device_state(struct usb_device *udev) >> >> if (udev->parent) { >> hub = usb_hub_to_struct_hub(udev->parent); >> - port_dev = hub->ports[udev->portnum - 1]; >> - WRITE_ONCE(port_dev->state, udev->state); >> - sysfs_notify_dirent(port_dev->state_kn); >> + >> + /* >> + * The Link Layer Validation System Driver (lvstest) >> + * has procedure of unbinding the hub before running >> + * the rest of the procedure. This triggers >> + * hub_disconnect will set the hub's maxchild to 0. > > I can't parse this sentence, s/th is missing... Thanks for the review. Maybe this would sound better? "This triggers hub_disconnect which will set hub's maxchild to 0" > >> + * This would result usb_hub_to_struct_hub in this >> + * function to return NULL. > > "This would result in usb_hub_to_struct_hub in this function > returning NULL", perhaps? yah sound better. Will take care of it in next version. Thanks, -Udipto