Re: [PATCH] wifi: ath6kl: Check that the read operation returns a data length of 0
From: Greg KH <gregkh@linuxfoundation.org>
Date: 2024-08-25 08:34:04
Also in:
linux-usb, linux-wireless, lkml
On Sun, Aug 25, 2024 at 04:14:17PM +0800, Edward Adam Davis wrote:
quoted hunk ↗ jump to hunk
On Sun, 25 Aug 2024 09:25:37 +0200, Greg KH wrote:quoted
quoted
If the data length returned by the device is 0, the read operation should be considered a failure. Reported-and-tested-by: syzbot+92c6dd14aaa230be6855@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis <redacted> --- drivers/net/wireless/ath/ath6kl/usb.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c index 5220809841a6..2a89bab81b24 100644 --- a/drivers/net/wireless/ath/ath6kl/usb.c +++ b/drivers/net/wireless/ath/ath6kl/usb.c@@ -1034,6 +1034,9 @@ static int ath6kl_usb_bmi_read(struct ath6kl *ar, u8 *buf, u32 len) ath6kl_err("Unable to read the bmi data from the device: %d\n", ret); return ret; + } else { + ath6kl_err("Actual read the bmi data length is 0 from the device\n"); + return -EIO;Close, but not quite there. ath6kl_usb_submit_ctrl_in() needs to verify that the actual amount of data was read that was asked for. If a short read happens (or a long one), then an error needs to propagate out, not just 0. See the "note:" line in that function for what needs to be properly checked. hope this helps,Thanks for your analysis. I have carefully read your analysis and I am not sure if the following understanding is appropriate:diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c index 2a89bab81b24..35884316a8c8 100644 --- a/drivers/net/wireless/ath/ath6kl/usb.c +++ b/drivers/net/wireless/ath/ath6kl/usb.c@@ -932,6 +932,15 @@ static int ath6kl_usb_submit_ctrl_in(struct ath6kl_usb *ar_usb, kfree(buf);
First off, this should be using usb_control_msg_send() instead of having to roll their own buffer handling, right?
+ /* There are two types of read failure situations that need to be captured:
+ * 1. short read: ret < size && ret >= 0
+ * 2. long read: ret > size
+ * */
+ if (req == ATH6KL_USB_CONTROL_REQ_RECV_BMI_RESP && ret != size) {
+ ath6kl_warn("Actual read the data length is: %d, but input size is %d\n", ret, size);
+ return -EIO;
+ }If you switch to usb_control_msg_send() this logic gets a lot simpler. Perhaps do that instead? If not, then you need to check for "short writes" or zero writes, see the documentation for usb_control_msg() for what it returns. Your comment is not correct here, there are 3 different return "states" that you need to handle. And why are you caring about what the req type is? thanks, greg k-h