| Message ID | 20220726032420.5516-1-duoming@zju.edu.cn (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v2] netrom: fix sleep in atomic context bugs in timer handlers | expand |
On Tue, 26 Jul 2022 11:24:20 +0800 Duoming Zhou wrote: > nr_heartbeat_expiry > nr_write_internal > nr_transmit_buffer void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb) { [...] if (!nr_route_frame(skb, NULL)) { > nr_route_frame int nr_route_frame(struct sk_buff *skb, ax25_cb *ax25) { [...] if (ax25 != NULL) { ret = nr_add_node(nr_src, "", &ax25->dest_addr, ax25->digipeat, ax25 must be NULL on this path AFAICT. > nr_add_node > kmemdup(..,GFP_KERNEL) //may sleep
Hello, On Wed, 27 Jul 2022 18:36:47 -0700 Jakub Kicinski wrote: > On Tue, 26 Jul 2022 11:24:20 +0800 Duoming Zhou wrote: > > nr_heartbeat_expiry > > nr_write_internal > > nr_transmit_buffer > > void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb) > { > [...] > if (!nr_route_frame(skb, NULL)) { > > > nr_route_frame > > int nr_route_frame(struct sk_buff *skb, ax25_cb *ax25) > { > [...] > if (ax25 != NULL) { > ret = nr_add_node(nr_src, "", &ax25->dest_addr, ax25->digipeat, > > ax25 must be NULL on this path AFAICT. > > > nr_add_node > > kmemdup(..,GFP_KERNEL) //may sleep Thank you for your time and suggestions, I understand. Best regards, Duoming Zhou
diff --git a/net/netrom/nr_route.c b/net/netrom/nr_route.c index baea3cbd76c..1ddcf13de6a 100644 --- a/net/netrom/nr_route.c +++ b/net/netrom/nr_route.c @@ -163,7 +163,7 @@ static int __must_check nr_add_node(ax25_address *nr, const char *mnemonic, if (ax25_digi != NULL && ax25_digi->ndigi > 0) { nr_neigh->digipeat = kmemdup(ax25_digi, sizeof(*ax25_digi), - GFP_KERNEL); + GFP_ATOMIC); if (nr_neigh->digipeat == NULL) { kfree(nr_neigh); if (nr_node)
There are sleep in atomic context bugs in timer handlers of netrom such as nr_t1timer_expiry(), nr_t2timer_expiry(), nr_heartbeat_expiry(), nr_idletimer_expiry() and so on. The root cause is kmemdup() with GFP_KERNEL parameter that may sleep could be called by different timer handlers which is in interrupt context. One of the call paths that could trigger bug is shown below: (interrupt context) nr_heartbeat_expiry nr_write_internal nr_transmit_buffer nr_route_frame nr_add_node kmemdup(..,GFP_KERNEL) //may sleep This patch changes gfp_t parameter of kmemdup in nr_add_node() from GFP_KERNEL to GFP_ATOMIC in order to prevent sleep in atomic context bugs. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- Changes in v2: - Correct the "Fixes" tag. net/netrom/nr_route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)