Messages in this thread | | | Subject | Re: [PATCH] r8a66597: Fix a possible concurrency use-after-free bug in r8a66597_endpoint_disable() | From | Jia-Ju Bai <> | Date | Tue, 18 Dec 2018 19:53:56 +0800 |
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On 2018/12/18 19:11, Greg KH wrote: > On Tue, Dec 18, 2018 at 06:00:20PM +0800, Jia-Ju Bai wrote: >> The function r8a66597_endpoint_disable() and r8a66597_urb_enqueue() may >> be concurrently executed. >> The two functions both access a possible shared variable "hep->hcpriv". >> >> This shared variable is freed by r8a66597_endpoint_disable() via the >> call path: >> r8a66597_endpoint_disable >> kfree(hep->hcpriv) (line 1995 in Linux-4.19) >> >> This variable is read by r8a66597_urb_enqueue() via the call path: >> r8a66597_urb_enqueue >> spin_lock_irqsave(&r8a66597->lock); >> init_pipe_info >> enable_r8a66597_pipe >> pipe = hep->hcpriv (line 802 in Linux-4.19) >> >> The read operation is protected by a spinlock, but the free operation >> is not protected by this spinlock, thus a concurrency use-after-free bug >> may occur. >> >> To fix this bug, the spin-lock and spin-unlock function calls in >> r8a66597_endpoint_disable() are moved to protect the free operation. >> >> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com> >> --- >> drivers/usb/host/r8a66597-hcd.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/usb/host/r8a66597-hcd.c b/drivers/usb/host/r8a66597-hcd.c >> index 984892dd72f5..1495ce14ad22 100644 >> --- a/drivers/usb/host/r8a66597-hcd.c >> +++ b/drivers/usb/host/r8a66597-hcd.c >> @@ -1991,13 +1991,14 @@ static void r8a66597_endpoint_disable(struct usb_hcd *hcd, >> return; >> pipenum = pipe->info.pipenum; >> >> + spin_lock_irqsave(&r8a66597->lock, flags); > Don't you also need the __aquires/__releases markings on this function > in order to properly annotate it, like the rest of the driver has?
Okay, thanks for this suggestion :) I will send a v2 patch.
Best wishes, Jia-Ju Bai
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