Commit 6fd916e2 authored Jun 15, 2020 by Zekun Shen Committed by Sasha Levin Jun 30, 2020

net: alx: fix race condition in alx_remove



[ Upstream commit e89df5c4322c1bf495f62d74745895b5fd2a4393 ]

There is a race condition exist during termination. The path is
alx_stop and then alx_remove. An alx_schedule_link_check could be called
before alx_stop by interrupt handler and invoke alx_link_check later.
Alx_stop frees the napis, and alx_remove cancels any pending works.
If any of the work is scheduled before termination and invoked before
alx_remove, a null-ptr-deref occurs because both expect alx->napis[i].

This patch fix the race condition by moving cancel_work_sync functions
before alx_free_napis inside alx_stop. Because interrupt handler can call
alx_schedule_link_check again, alx_free_irq is moved before
cancel_work_sync calls too.

Signed-off-by: Zekun Shen <bruceshenzk@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 855dbf10

drivers/net/ethernet/atheros/alx/main.c

+5 −4

Original line number	Diff line number	Diff line
		@@ -1249,8 +1249,12 @@ static int __alx_open(struct alx_priv *alx, bool resume)

		static void __alx_stop(struct alx_priv *alx)
		{
		alx_halt(alx);
		alx_free_irq(alx);

		cancel_work_sync(&alx->link_check_wk);
		cancel_work_sync(&alx->reset_wk);

		alx_halt(alx);
		alx_free_rings(alx);
		alx_free_napis(alx);
		}
		@@ -1858,9 +1862,6 @@ static void alx_remove(struct pci_dev *pdev)
		struct alx_priv *alx = pci_get_drvdata(pdev);
		struct alx_hw *hw = &alx->hw;

		cancel_work_sync(&alx->link_check_wk);
		cancel_work_sync(&alx->reset_wk);

		/* restore permanent mac address */
		alx_set_macaddr(hw, hw->perm_addr);