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Wed, 23 Sep 2026 02:30:00 -0700 (PDT) Received: from [10.214.128.75] ([149.7.5.83]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49fde197466sm58177785e9.7.2026.09.23.02.29.55 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 23 Sep 2026 02:29:59 -0700 (PDT) Message-ID: Date: Wed, 23 Sep 2026 03:29:50 -0600 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] usbip: stub: keep URB array state consistent on errors To: Weiming Shi , Valentina Manea , Shuah Khan , Hongren Zheng , Greg Kroah-Hartman Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Suwan Kim , co+66c3f58096d0bde8@bugs.sh, Xiang Mei , stable@vger.kernel.org, Shuah Khan References: <20260912083925.587987-2-bestswngs@gmail.com> Content-Language: en-US From: Shuah Khan In-Reply-To: <20260912083925.587987-2-bestswngs@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/12/26 02:39, Weiming Shi wrote: > stub_priv_alloc() links a zeroed stub_priv to priv_init before the URB > array is allocated. The error handler may therefore consume the object > after stub_recv_cmd_submit() reports SDEV_EVENT_ERROR_MALLOC. > > Do not publish num_urbs until the array exists. If a later URB allocation > fails, clear the freed array pointer and count before the event handler can > walk them. This prevents a NULL dereference on array-allocation failure > and freed-array reads that can lead to invalid URB use or a double free on > later failures. How is this problem reproduced? Why is this a problem in this code path? > > Fixes: ea44d190764b ("usbip: Implement SG support to vhci-hcd and stub driver") > Cc: stable@vger.kernel.org # 5.4+ > Reported-by: co+66c3f58096d0bde8@bugs.sh > Closes: https://lore.kernel.org/all/J3vQPnNHSkQ6YUiFvu1bk8ai3Q8aZ7a9J1Y7%40bugs.sh/ > Assisted-by: Codex:gpt-5 > Signed-off-by: Weiming Shi > --- > drivers/usb/usbip/stub_rx.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/usb/usbip/stub_rx.c b/drivers/usb/usbip/stub_rx.c > index 1e9ae578810d9..33058fb05b2f4 100644 > --- a/drivers/usb/usbip/stub_rx.c > +++ b/drivers/usb/usbip/stub_rx.c > @@ -534,10 +534,10 @@ static void stub_recv_cmd_submit(struct stub_device *sdev, > } > > /* allocate urb array */ > - priv->num_urbs = num_urbs; > priv->urbs = kmalloc_objs(*priv->urbs, num_urbs); > if (!priv->urbs) > goto err_urbs; > + priv->num_urbs = num_urbs; > > /* setup a urb */ > if (support_sg) { > @@ -641,6 +641,8 @@ static void stub_recv_cmd_submit(struct stub_device *sdev, > > err_urb: > kfree(priv->urbs); > + priv->urbs = NULL; > + priv->num_urbs = 0; > err_urbs: > kfree(buffer); > sgl_free(sgl); thanks, -- Shuah