From: Michał Pecio <michal.pecio@gmail.com> stable inclusion from stable-v6.6.89 commit 142273a49f2c315eabdbdf5a71c15e479b75ca91 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IC6BMN CVE: CVE-2025-37813 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- 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... Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Tong Tiangen <tongtiangen@huawei.com> --- drivers/usb/host/xhci-ring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 9d3f1cfe388d..5a4eb1270b60 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -3878,7 +3878,7 @@ 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); -- 2.25.1