This is a note to let you know that I've just added the patch titled
usb: xhci: Fix NULL pointer dereference on certain command aborts
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-xhci-fix-null-pointer-dereference-on-certain-com.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 2cce2f007b6466988a4182b6b0a5a3e229741003
Author: Michal Pecio <michal.pecio@xxxxxxxxx>
Date: Fri Dec 27 14:01:40 2024 +0200
usb: xhci: Fix NULL pointer dereference on certain command aborts
[ Upstream commit 1e0a19912adb68a4b2b74fd77001c96cd83eb073 ]
If a command is queued to the final usable TRB of a ring segment, the
enqueue pointer is advanced to the subsequent link TRB and no further.
If the command is later aborted, when the abort completion is handled
the dequeue pointer is advanced to the first TRB of the next segment.
If no further commands are queued, xhci_handle_stopped_cmd_ring() sees
the ring pointers unequal and assumes that there is a pending command,
so it calls xhci_mod_cmd_timer() which crashes if cur_cmd was NULL.
Don't attempt timer setup if cur_cmd is NULL. The subsequent doorbell
ring likely is unnecessary too, but it's harmless. Leave it alone.
This is probably Bug 219532, but no confirmation has been received.
The issue has been independently reproduced and confirmed fixed using
a USB MCU programmed to NAK the Status stage of SET_ADDRESS forever.
Everything continued working normally after several prevented crashes.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219532
Fixes: c311e391a7ef ("xhci: rework command timeout and cancellation,")
CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Michal Pecio <michal.pecio@xxxxxxxxx>
Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20241227120142.1035206-4-mathias.nyman@xxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 97b192058ffe4..64bf50ea62a49 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -380,7 +380,8 @@ static void xhci_handle_stopped_cmd_ring(struct xhci_hcd *xhci,
if ((xhci->cmd_ring->dequeue != xhci->cmd_ring->enqueue) &&
!(xhci->xhc_state & XHCI_STATE_DYING)) {
xhci->current_cmd = cur_cmd;
- xhci_mod_cmd_timer(xhci);
+ if (cur_cmd)
+ xhci_mod_cmd_timer(xhci);
xhci_ring_cmd_db(xhci);
}
}
