summaryrefslogtreecommitdiff
path: root/drivers/usb/dwc2
diff options
context:
space:
mode:
authorJia-Ju Bai <baijiaju@buaa.edu.cn>2023-09-26 05:44:04 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-10-02 14:57:47 +0300
commitef307bc6ef04e8c1ea843231db58e3afaafa9fa6 (patch)
treeed13cfe663fcf8b018f1cf42e9b095ab2eb3cea2 /drivers/usb/dwc2
parenta60359ea32251399c00d934981f5a6fa25ec917f (diff)
downloadlinux-ef307bc6ef04e8c1ea843231db58e3afaafa9fa6.tar.xz
usb: dwc2: fix possible NULL pointer dereference caused by driver concurrency
In _dwc2_hcd_urb_enqueue(), "urb->hcpriv = NULL" is executed without holding the lock "hsotg->lock". In _dwc2_hcd_urb_dequeue(): spin_lock_irqsave(&hsotg->lock, flags); ... if (!urb->hcpriv) { dev_dbg(hsotg->dev, "## urb->hcpriv is NULL ##\n"); goto out; } rc = dwc2_hcd_urb_dequeue(hsotg, urb->hcpriv); // Use urb->hcpriv ... out: spin_unlock_irqrestore(&hsotg->lock, flags); When _dwc2_hcd_urb_enqueue() and _dwc2_hcd_urb_dequeue() are concurrently executed, the NULL check of "urb->hcpriv" can be executed before "urb->hcpriv = NULL". After urb->hcpriv is NULL, it can be used in the function call to dwc2_hcd_urb_dequeue(), which can cause a NULL pointer dereference. This possible bug is found by an experimental static analysis tool developed by myself. This tool analyzes the locking APIs to extract function pairs that can be concurrently executed, and then analyzes the instructions in the paired functions to identify possible concurrency bugs including data races and atomicity violations. The above possible bug is reported, when my tool analyzes the source code of Linux 6.5. To fix this possible bug, "urb->hcpriv = NULL" should be executed with holding the lock "hsotg->lock". After using this patch, my tool never reports the possible bug, with the kernelconfiguration allyesconfig for x86_64. Because I have no associated hardware, I cannot test the patch in runtime testing, and just verify it according to the code logic. Fixes: 33ad261aa62b ("usb: dwc2: host: spinlock urb_enqueue") Signed-off-by: Jia-Ju Bai <baijiaju@buaa.edu.cn> Link: https://lore.kernel.org/r/20230926024404.832096-1-baijiaju@buaa.edu.cn Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/usb/dwc2')
-rw-r--r--drivers/usb/dwc2/hcd.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 657f1f659ffa..35c7a4df8e71 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -4769,8 +4769,8 @@ fail3:
if (qh_allocated && qh->channel && qh->channel->qh == qh)
qh->channel->qh = NULL;
fail2:
- spin_unlock_irqrestore(&hsotg->lock, flags);
urb->hcpriv = NULL;
+ spin_unlock_irqrestore(&hsotg->lock, flags);
kfree(qtd);
fail1:
if (qh_allocated) {