Julian Calaby [off-list ref] writes:
Hi Dongliang,
(Drive-by review, I know almost nothing about the code in question)
On Fri, Jul 9, 2021 at 6:47 PM Dongliang Mu [off-list ref] wrote:
quoted
The commit 03fb92a432ea ("ath9k: hif_usb: fix race condition between
usb_get_urb() and usb_kill_anchored_urbs()") adds three usb_get_urb
in ath9k_hif_usb_dealloc_tx_urbs and usb_free_urb.
Fix this bug by adding corresponding usb_free_urb in
ath9k_hif_usb_dealloc_tx_urbs other and hif_usb_stop.
Reported-by: <redacted>
Fixes: 03fb92a432ea ("ath9k: hif_usb: fix race condition between usb_get_urb() and usb_kill_anchored_urbs()")
Signed-off-by: Dongliang Mu <redacted>
---
drivers/net/wireless/ath/ath9k/hif_usb.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 860da13bfb6a..bda91ff3289b 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -457,6 +457,7 @@ static void hif_usb_stop(void *hif_handle)
usb_kill_urb(tx_buf->urb);
list_del(&tx_buf->list);
usb_free_urb(tx_buf->urb);
+ usb_free_urb(tx_buf->urb);
Ok, so if I'm reading this correctly, before the first usb_free_urb()
call, we have two references to the urb at tx_buf->urb.
Why?
Isn't the better fix here to detangle why there's more than one
reference to it and resolve it that way? This looks like a hack to fix
something much more fundamentally broken.
Yeah, this looks very suspicious.
One more thing: also the patch should be tested with real hardware. I'm
worried that people are just trying to fix a syzbot warning and not
really considering how it works in real life. That's why I'm extra
careful with syzbot patches for wireless drivers.
--
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