2022-08-27 16:03:02

by Duoming Zhou

Subject: [PATCH net] ethernet: rocker: fix sleep in atomic context bug in neigh_timer_handler

The function neigh_timer_handler() is a timer handler that runs in an
atomic context. When used by rocker, neigh_timer_handler() calls
"kzalloc(.., GFP_KERNEL)" that may sleep. As a result, the sleep in
atomic context bug will happen. One of the processes is shown below:

ofdpa_fib4_add()
...
neigh_add_timer()

(wait a timer)

neigh_timer_handler()
neigh_release()
neigh_destroy()
rocker_port_neigh_destroy()
rocker_world_port_neigh_destroy()
ofdpa_port_neigh_destroy()
ofdpa_port_ipv4_neigh()
kzalloc(sizeof(.., GFP_KERNEL) //may sleep

This patch changes the gfp_t parameter of kzalloc() from GFP_KERNEL to
GFP_ATOMIC in order to mitigate the bug.

Fixes: 00fc0c51e35b ("rocker: Change world_ops API and implementation to be switchdev independant")
Signed-off-by: Duoming Zhou <[email protected]>
---
drivers/net/ethernet/rocker/rocker_ofdpa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/rocker/rocker_ofdpa.c b/drivers/net/ethernet/rocker/rocker_ofdpa.c
index bc70c6abd6a..58cf7cc54f4 100644
--- a/drivers/net/ethernet/rocker/rocker_ofdpa.c
+++ b/drivers/net/ethernet/rocker/rocker_ofdpa.c
@@ -1273,7 +1273,7 @@ static int ofdpa_port_ipv4_neigh(struct ofdpa_port *ofdpa_port,
bool removing;
int err = 0;

- entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+ entry = kzalloc(sizeof(*entry), GFP_ATOMIC);
if (!entry)
return -ENOMEM;

--
2.17.1

2022-08-31 13:35:41

by patchwork-bot+netdevbpf

Subject: Re: [PATCH net] ethernet: rocker: fix sleep in atomic context bug in neigh_timer_handler

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <[email protected]>:

On Sat, 27 Aug 2022 23:38:15 +0800 you wrote:
> The function neigh_timer_handler() is a timer handler that runs in an
> atomic context. When used by rocker, neigh_timer_handler() calls
> "kzalloc(.., GFP_KERNEL)" that may sleep. As a result, the sleep in
> atomic context bug will happen. One of the processes is shown below:
>
> ofdpa_fib4_add()
> ...
> neigh_add_timer()
>
> [...]

Here is the summary with links:
- [net] ethernet: rocker: fix sleep in atomic context bug in neigh_timer_handler
https://git.kernel.org/netdev/net/c/c0955bf957be

You are awesome, thank you!
--
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