[PATCH v14 02/53] xhci: fix off by one check when adding a secondary interrupter.

From: Wesley Cheng
Date: Thu Feb 08 2024 - 18:16:29 EST

From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

The sanity check of interrupter index when adding a new interrupter is
off by one. intr_num needs to be smaller than xhci->max_interrupter to
fit the array of interrupters.

Luckily this doesn't cause any real word harm as xhci_add_interrupter()
is always called with a intr_num value smaller than xhci->max_interrupters
in any current kernel.

Should not be needed for stable as 6.7 kernel and older only supports
one interrupter, with intr_num always being zero.

Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-usb/e9771296-586d-456a-ac24-a82de79bb2e6@moroto.mountain/
Fixes: 4bf398e15aa4 ("xhci: split allocate interrupter into separate alloacte and add parts")
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20240125152737.2983959-3-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 | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index d00d4d937236..a7716202a8dd 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -2322,7 +2322,7 @@ xhci_add_interrupter(struct xhci_hcd *xhci, struct xhci_interrupter *ir,
u64 erst_base;
u32 erst_size;

- if (intr_num > xhci->max_interrupters) {
+ if (intr_num >= xhci->max_interrupters) {
xhci_warn(xhci, "Can't add interrupter %d, max interrupters %d\n",
intr_num, xhci->max_interrupters);
return -EINVAL;