From fa6b063e200255a109f06388dd344766be4cd553 Mon Sep 17 00:00:00 2001 From: Alexander Kappner Date: Thu, 21 Dec 2017 15:06:14 +0200 Subject: [PATCH] UPSTREAM: xhci: Fix use-after-free in xhci debugfs Trying to read from debugfs after the system has resumed from hibernate causes a use-after-free and thus a protection fault. Steps to reproduce: Hibernate system, resume from hibernate, then run $ cat /sys/kernel/debug/usb/xhci/*/command-ring/enqueue [ 3902.765086] general protection fault: 0000 [#1] PREEMPT SMP ... [ 3902.765136] RIP: 0010:xhci_trb_virt_to_dma.part.50+0x5/0x30 ... [ 3902.765178] Call Trace: [ 3902.765188] xhci_ring_enqueue_show+0x1e/0x40 [ 3902.765197] seq_read+0xdb/0x3a0 [ 3902.765204] ? __handle_mm_fault+0x5fb/0x1210 [ 3902.765211] full_proxy_read+0x4a/0x70 [ 3902.765219] __vfs_read+0x23/0x120 [ 3902.765228] vfs_read+0x8e/0x130 [ 3902.765235] SyS_read+0x42/0x90 [ 3902.765242] do_syscall_64+0x6b/0x290 [ 3902.765251] entry_SYSCALL64_slow_path+0x25/0x25 The issue is caused by the xhci ring structures being reallocated when the system is resumed, but pointers to the old structures being retained in the debugfs files "private" field: The proposed patch fixes this issue by storing a pointer to the xhci_ring field in the xhci device structure in debugfs rather than directly storing a pointer to the xhci_ring. Change-Id: Ic60c7b4c7599209b89775e03b5cc4f9d9cdba6ac Fixes: 02b6fdc2a153 ("usb: xhci: Add debugfs interface for xHCI driver") Signed-off-by: Alexander Kappner Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman Signed-off-by: William Wu --- drivers/usb/host/xhci-debugfs.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/usb/host/xhci-debugfs.c b/drivers/usb/host/xhci-debugfs.c index 833efbb4132f..b4b59da335d0 100644 --- a/drivers/usb/host/xhci-debugfs.c +++ b/drivers/usb/host/xhci-debugfs.c @@ -141,7 +141,7 @@ static void xhci_debugfs_regset(struct xhci_hcd *xhci, u32 base, static int xhci_ring_enqueue_show(struct seq_file *s, void *unused) { dma_addr_t dma; - struct xhci_ring *ring = s->private; + struct xhci_ring *ring = *(struct xhci_ring **)s->private; dma = xhci_trb_virt_to_dma(ring->enq_seg, ring->enqueue); seq_printf(s, "%pad\n", &dma); @@ -152,7 +152,7 @@ static int xhci_ring_enqueue_show(struct seq_file *s, void *unused) static int xhci_ring_dequeue_show(struct seq_file *s, void *unused) { dma_addr_t dma; - struct xhci_ring *ring = s->private; + struct xhci_ring *ring = *(struct xhci_ring **)s->private; dma = xhci_trb_virt_to_dma(ring->deq_seg, ring->dequeue); seq_printf(s, "%pad\n", &dma); @@ -162,7 +162,7 @@ static int xhci_ring_dequeue_show(struct seq_file *s, void *unused) static int xhci_ring_cycle_show(struct seq_file *s, void *unused) { - struct xhci_ring *ring = s->private; + struct xhci_ring *ring = *(struct xhci_ring **)s->private; seq_printf(s, "%d\n", ring->cycle_state); @@ -325,7 +325,7 @@ static void xhci_debugfs_create_files(struct xhci_hcd *xhci, } static struct dentry *xhci_debugfs_create_ring_dir(struct xhci_hcd *xhci, - struct xhci_ring *ring, + struct xhci_ring **ring, const char *name, struct dentry *parent) { @@ -366,7 +366,7 @@ void xhci_debugfs_create_endpoint(struct xhci_hcd *xhci, snprintf(epriv->name, sizeof(epriv->name), "ep%02d", ep_index); epriv->root = xhci_debugfs_create_ring_dir(xhci, - dev->eps[ep_index].new_ring, + &dev->eps[ep_index].new_ring, epriv->name, spriv->root); spriv->eps[ep_index] = epriv; @@ -402,7 +402,7 @@ void xhci_debugfs_create_slot(struct xhci_hcd *xhci, int slot_id) priv->dev = dev; dev->debugfs_private = priv; - xhci_debugfs_create_ring_dir(xhci, dev->eps[0].ring, + xhci_debugfs_create_ring_dir(xhci, &dev->eps[0].ring, "ep00", priv->root); xhci_debugfs_create_context_files(xhci, priv->root, slot_id); @@ -452,11 +452,11 @@ void xhci_debugfs_init(struct xhci_hcd *xhci) xhci_runtime_regs, ARRAY_SIZE(xhci_runtime_regs), xhci->debugfs_root, "reg-runtime"); - xhci_debugfs_create_ring_dir(xhci, xhci->cmd_ring, + xhci_debugfs_create_ring_dir(xhci, &xhci->cmd_ring, "command-ring", xhci->debugfs_root); - xhci_debugfs_create_ring_dir(xhci, xhci->event_ring, + xhci_debugfs_create_ring_dir(xhci, &xhci->event_ring, "event-ring", xhci->debugfs_root);