2018-09-01 12:12:30

by Jia-Ju Bai

Subject: [PATCH] net: cadence: Fix a sleep-in-atomic-context bug in macb_halt_tx()

The kernel module may sleep with holding a spinlock.

The function call paths (from bottom to top) in Linux-4.16 are:

[FUNC] usleep_range
drivers/net/ethernet/cadence/macb_main.c, 648:
usleep_range in macb_halt_tx
drivers/net/ethernet/cadence/macb_main.c, 730:
macb_halt_tx in macb_tx_error_task
drivers/net/ethernet/cadence/macb_main.c, 721:
_raw_spin_lock_irqsave in macb_tx_error_task

To fix this bug, usleep_range() is replaced with udelay().

This bug is found by my static analysis tool DSAC.

Signed-off-by: Jia-Ju Bai <[email protected]>
---
drivers/net/ethernet/cadence/macb_main.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index a6c911bb5ce2..3dcc31cd4261 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -641,7 +641,7 @@ static int macb_halt_tx(struct macb *bp)
if (!(status & MACB_BIT(TGO)))
return 0;

- usleep_range(10, 250);
+ udelay(250);
} while (time_before(halt_time, timeout));

return -ETIMEDOUT;
--
2.17.0

2018-09-02 23:08:22

by David Miller

Subject: Re: [PATCH] net: cadence: Fix a sleep-in-atomic-context bug in macb_halt_tx()

From: Jia-Ju Bai <[email protected]>
Date: Sat, 1 Sep 2018 20:11:05 +0800

> The kernel module may sleep with holding a spinlock.
>
> The function call paths (from bottom to top) in Linux-4.16 are:
>
> [FUNC] usleep_range
> drivers/net/ethernet/cadence/macb_main.c, 648:
> usleep_range in macb_halt_tx
> drivers/net/ethernet/cadence/macb_main.c, 730:
> macb_halt_tx in macb_tx_error_task
> drivers/net/ethernet/cadence/macb_main.c, 721:
> _raw_spin_lock_irqsave in macb_tx_error_task
>
> To fix this bug, usleep_range() is replaced with udelay().
>
> This bug is found by my static analysis tool DSAC.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>

Applied, thanks.