diff options
| author | Michal Pecio <michal.pecio@gmail.com> | 2025-04-10 18:18:26 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-02 07:59:12 +0200 |
| commit | bce3055b08e303e28a8751f6073066f5c33a0744 (patch) | |
| tree | a94b0fa41838514baeb6bad69a07d18ac7a37779 | |
| parent | 1777714865086ec33f222c398cb273d815a95c2a (diff) | |
usb: xhci: Fix invalid pointer dereference in Etron workaround
commit 1ea050da5562af9b930d17cbbe9632d30f5df43a upstream.
This check is performed before prepare_transfer() and prepare_ring(), so
enqueue can already point at the final link TRB of a segment. And indeed
it will, some 0.4% of times this code is called.
Then enqueue + 1 is an invalid pointer. It will crash the kernel right
away or load some junk which may look like a link TRB and cause the real
link TRB to be replaced with a NOOP. This wouldn't end well.
Use a functionally equivalent test which doesn't dereference the pointer
and always gives correct result.
Something has crashed my machine twice in recent days while playing with
an Etron HC, and a control transfer stress test ran for confirmation has
just crashed it again. The same test passes with this patch applied.
Fixes: 5e1c67abc930 ("xhci: Fix control transfer error on Etron xHCI host")
Cc: stable@vger.kernel.org
Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Reviewed-by: Kuangyi Chiang <ki.chiang65@gmail.com>
Link: https://lore.kernel.org/r/20250410151828.2868740-5-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/host/xhci-ring.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 2fad9563dca4..f3266fe406ba 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -3778,7 +3778,7 @@ int xhci_queue_ctrl_tx(struct xhci_hcd *xhci, gfp_t mem_flags, * enqueue a No Op TRB, this can prevent the Setup and Data Stage * TRB to be breaked by the Link TRB. */ - if (trb_is_link(ep_ring->enqueue + 1)) { + if (last_trb_on_seg(ep_ring->enq_seg, ep_ring->enqueue + 1)) { field = TRB_TYPE(TRB_TR_NOOP) | ep_ring->cycle_state; queue_trb(xhci, ep_ring, false, 0, 0, TRB_INTR_TARGET(0), field); |