Commit c130b666 authored Dec 28, 2016 by Gabriel Krisman Bertazi Committed by Greg Kroah-Hartman Jan 11, 2017

8250_pci: Fix potential use-after-free in error path



Commit f209fa03 ("serial: 8250_pci: Detach low-level driver during
PCI error recovery") introduces a potential use-after-free in case the
pciserial_init_ports call in serial8250_io_resume fails, which may
happen if a memory allocation fails or if the .init quirk failed for
whatever reason).  If this happen, further pci_get_drvdata will return a
pointer to freed memory.

This patch reworks the PCI recovery resume hook to restore the old priv
structure in this case, which should be ok, since the ports were already
detached. Such error during recovery causes us to give up on the
recovery.

Fixes: f209fa03 ("serial: 8250_pci: Detach low-level driver during
  PCI error recovery")
Reported-by: Michal Suchanek <msuchanek@suse.com>
Signed-off-by: Gabriel Krisman Bertazi <krisman@linux.vnet.ibm.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent b389f173

drivers/tty/serial/8250/8250_pci.c

+5 −7

Original line number	Diff line number	Diff line
		@@ -5642,17 +5642,15 @@ static pci_ers_result_t serial8250_io_slot_reset(struct pci_dev *dev)
		static void serial8250_io_resume(struct pci_dev *dev)
		{
		struct serial_private *priv = pci_get_drvdata(dev);
		const struct pciserial_board *board;
		struct serial_private *new;

		if (!priv)
		return;

		board = priv->board;
		new = pciserial_init_ports(dev, priv->board);
		if (!IS_ERR(new)) {
		pci_set_drvdata(dev, new);
		kfree(priv);
		priv = pciserial_init_ports(dev, board);

		if (!IS_ERR(priv)) {
		pci_set_drvdata(dev, priv);
		}
		}