| Message ID | 20220723035646.29857-1-duoming@zju.edu.cn (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] netrom: fix sleep in atomic context bugs in timer handlers | expand |
On Sat, 23 Jul 2022 11:56:46 +0800 Duoming Zhou wrote:
> Fixes: eafff86d3bd8 ("[NETROM]: Use kmemdup")
That's not a correct Fixes tag, acme just swapped kmalloc for kmemdup().
The allocate flags did not change.
Hello, On Mon, 25 Jul 2022 19:49:30 -0700 Jakub Kicinski wrote: > On Sat, 23 Jul 2022 11:56:46 +0800 Duoming Zhou wrote: > > Fixes: eafff86d3bd8 ("[NETROM]: Use kmemdup") > > That's not a correct Fixes tag, acme just swapped kmalloc for kmemdup(). > The allocate flags did not change. Thanks for your time and reply! The correct Fixes tag is "Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")". The following is the code: https://elixir.bootlin.com/linux/v2.6.12-rc2/source/net/netrom/nr_route.c#L158 ... if ((nr_neigh->digipeat = kmalloc(sizeof(*ax25_digi), GFP_KERNEL)) == NULL) { ... 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: eafff86d3bd8 ("[NETROM]: Use kmemdup") Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> --- net/netrom/nr_route.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)