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net: alx: fix race condition in alx_remove

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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>
This commit is contained in:
Zekun Shen 2020-06-15 11:50:29 -04:00 committed by David S. Miller
parent dff515a3e7
commit e89df5c432
1 changed files with 5 additions and 4 deletions
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9
drivers/net/ethernet/atheros/alx/main.c
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@ -1249,8 +1249,12 @@ out_disable_adv_intr:
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);
}
@ -1855,9 +1859,6 @@ 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);