This is a note to let you know that I've just added the patch titled net: alx: fix race condition in alx_remove to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-alx-fix-race-condition-in-alx_remove.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 2abbff41927b65e495d0ccac838192a52f404dbc Author: Zekun Shen <bruceshenzk@xxxxxxxxx> Date: Mon Jun 15 11:50:29 2020 -0400 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@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/atheros/alx/main.c b/drivers/net/ethernet/atheros/alx/main.c index 6d32211349275..dd63b993ce7b3 100644 --- a/drivers/net/ethernet/atheros/alx/main.c +++ b/drivers/net/ethernet/atheros/alx/main.c @@ -1250,8 +1250,12 @@ 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); } @@ -1861,9 +1865,6 @@ 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);