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usb: xhci: Check for xhci->interrupters being allocated in xhci_mem_clearup()

PATCH In review Marc Zyngier 2 participants 2 messages Jul 31, 2024 – Aug 5, 2024

Subsystems (2)
USB USB xHCI driver
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Marc Zyngier

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#0 lore raw

PATCH 1/1 usb: xhci: Check for xhci->interrupters being allocated in xhci_mem_clearup()

If xhci_mem_init() fails, it calls into xhci_mem_cleanup() to mop up the damage. If it fails early enough, before xhci->interrupters is allocated but after xhci->max_interrupters has been set, which happens in most (all?) cases, things get uglier, as xhci_mem_cleanup() unconditionally derefences xhci->interrupters. With prejudice.

Gate the interrupt freeing loop with a check on xhci->interrupters being non-NULL.

Found while debugging a DMA allocation issue that led the XHCI driver on this exact path.

Fixes c99b38c41234 ("xhci: add support to allocate several interrupters")
Cc Mathias Nyman <[email protected]>
Cc Wesley Cheng <[email protected]>
Cc Greg Kroah-Hartman <[email protected]>
Signed-off-by Marc Zyngier <[email protected]>
---
 drivers/usb/host/xhci-mem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
drivers/usb/host/xhci-mem.c +1 -1
index d7654f475daf..937ce5fd5809 100644
@@ -1872,7 +1872,7 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 
 	cancel_delayed_work_sync(&xhci->cmd_timer);
 
-	for (i = 0; i < xhci->max_interrupters; i++) {
+	for (i = 0; xhci->interrupters && i < xhci->max_interrupters; i++) {
 		if (xhci->interrupters[i]) {
 			xhci_remove_interrupter(xhci, xhci->interrupters[i]);
 			xhci_free_interrupter(xhci, xhci->interrupters[i]);
Signature · 1 line
2.39.2
#1 lore raw
Quoted 12 lines · Marc Zyngier

If xhci_mem_init() fails, it calls into xhci_mem_cleanup() to mop up the damage. If it fails early enough, before xhci->interrupters is allocated but after xhci->max_interrupters has been set, which happens in most (all?) cases, things get uglier, as xhci_mem_cleanup() unconditionally derefences xhci->interrupters. With prejudice.

Gate the interrupt freeing loop with a check on xhci->interrupters being non-NULL.

Found while debugging a DMA allocation issue that led the XHCI driver on this exact path.

Quoted 6 lines
Fixes c99b38c41234 ("xhci: add support to allocate several interrupters")
Cc Mathias Nyman <[email protected]>
Cc Wesley Cheng <[email protected]>
Cc Greg Kroah-Hartman <[email protected]>
Signed-off-by Marc Zyngier <[email protected]>

---

Thanks, Adding to queue

-Mathias