[PATCH v14 01/53] xhci: fix possible null pointer dereference at secondary interrupter removal

[Wesley Cheng]

From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

Don't try to remove a secondary interrupter that is known to be invalid.
Also check if the interrupter is valid inside the spinlock that protects
the array of interrupters.

Found by smatch static checker

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-usb/ffaa0a1b-5984-4a1f-bfd3-9184630a97b9@moroto.mountain/
Fixes: c99b38c41234 ("xhci: add support to allocate several interrupters")
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240125152737.2983959-2-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
---
 drivers/usb/host/xhci-mem.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 4460fa7e9fab..d00d4d937236 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -1861,14 +1861,14 @@ void xhci_remove_secondary_interrupter(struct usb_hcd *hcd, struct xhci_interrup
 	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
 	unsigned int intr_num;
 
+	spin_lock_irq(&xhci->lock);
+
 	/* interrupter 0 is primary interrupter, don't touch it */
-	if (!ir || !ir->intr_num || ir->intr_num >= xhci->max_interrupters)
+	if (!ir || !ir->intr_num || ir->intr_num >= xhci->max_interrupters) {
 		xhci_dbg(xhci, "Invalid secondary interrupter, can't remove\n");
-
-	/* fixme, should we check xhci->interrupter[intr_num] == ir */
-	/* fixme locking */
-
-	spin_lock_irq(&xhci->lock);
+		spin_unlock_irq(&xhci->lock);
+		return;
+	}
 
 	intr_num = ir->intr_num;