[PATCH] net: genetlink: Move initialization to core_initcall

[PATCH] net: genetlink: Move initialization to core_initcall

[Daniel Lezcano]

The generic netlink is initialized far after the netlink protocol
itself at subsys_initcall. The devlink is initialized at the same
level, but after, as shown by a disassembly of the vmlinux:

[ ... ]
374 ffff8000115f22c0 <__initcall_devlink_init4>:
375 ffff8000115f22c4 <__initcall_genl_init4>:
[ ... ]

The function devlink_init() calls genl_register_family() before the
generic netlink subsystem is initialized.

As the generic netlink initcall level is set since 2005, it seems that
was not a problem, but now we have the thermal framework initialized
at the core_initcall level which creates the generic netlink family
and sends a notification which leads to a subtle memory corruption
only detectable when the CONFIG_INIT_ON_ALLOC_DEFAULT_ON option is set
with the earlycon at init time.

The thermal framework needs to be initialized early in order to begin
the mitigation as soon as possible. Moving it to postcore_initcall is
acceptable.

This patch changes the initialization level for the generic netlink
family to the core_initcall and comes after the netlink protocol
initialization.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 net/netlink/genetlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 55ee680e9db1..36b8a1909826 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1263,7 +1263,7 @@ static int __init genl_init(void)
 	panic("GENL: Cannot register controller: %d\n", err);
 }
 
-subsys_initcall(genl_init);
+core_initcall(genl_init);
 
 static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
 			 gfp_t flags)
-- 
2.17.1

Re: [PATCH] net: genetlink: Move initialization to core_initcall

[Daniel Lezcano]

Hi Dave,

if you agree with this change, is it possible I merge it through the
thermal tree in order to fix the issue ?

Thanks

  -- Daniel


On 15/07/2020 09:41, Daniel Lezcano wrote:
> The generic netlink is initialized far after the netlink protocol
> itself at subsys_initcall. The devlink is initialized at the same
> level, but after, as shown by a disassembly of the vmlinux:
> 
> [ ... ]
> 374 ffff8000115f22c0 <__initcall_devlink_init4>:
> 375 ffff8000115f22c4 <__initcall_genl_init4>:
> [ ... ]
> 
> The function devlink_init() calls genl_register_family() before the
> generic netlink subsystem is initialized.
> 
> As the generic netlink initcall level is set since 2005, it seems that
> was not a problem, but now we have the thermal framework initialized
> at the core_initcall level which creates the generic netlink family
> and sends a notification which leads to a subtle memory corruption
> only detectable when the CONFIG_INIT_ON_ALLOC_DEFAULT_ON option is set
> with the earlycon at init time.
> 
> The thermal framework needs to be initialized early in order to begin
> the mitigation as soon as possible. Moving it to postcore_initcall is
> acceptable.
> 
> This patch changes the initialization level for the generic netlink
> family to the core_initcall and comes after the netlink protocol
> initialization.
> 
> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> ---
>  net/netlink/genetlink.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
> index 55ee680e9db1..36b8a1909826 100644
> --- a/net/netlink/genetlink.c
> +++ b/net/netlink/genetlink.c
> @@ -1263,7 +1263,7 @@ static int __init genl_init(void)
>  	panic("GENL: Cannot register controller: %d\n", err);
>  }
>  
> -subsys_initcall(genl_init);
> +core_initcall(genl_init);
>  
>  static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
>  			 gfp_t flags)
> 


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Re: [PATCH] net: genetlink: Move initialization to core_initcall

[David Miller]

From: Daniel Lezcano <daniel.lezcano@linaro.org>
Date: Wed, 15 Jul 2020 09:43:00 +0200

> if you agree with this change, is it possible I merge it through the
> thermal tree in order to fix the issue ?

No problem:

Acked-by: David S. Miller <davem@davemloft.net>

Re: [PATCH] net: genetlink: Move initialization to core_initcall

[Daniel Lezcano]

On 17/07/2020 19:34, David Miller wrote:
> From: Daniel Lezcano <daniel.lezcano@linaro.org>
> Date: Wed, 15 Jul 2020 09:43:00 +0200
> 
>> if you agree with this change, is it possible I merge it through the
>> thermal tree in order to fix the issue ?
> 
> No problem:
> 
> Acked-by: David S. Miller <davem@davemloft.net>

Thanks!


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Re: [PATCH] net: genetlink: Move initialization to core_initcall

[Marek Szyprowski]

Hi

On 15.07.2020 09:41, Daniel Lezcano wrote:
> The generic netlink is initialized far after the netlink protocol
> itself at subsys_initcall. The devlink is initialized at the same
> level, but after, as shown by a disassembly of the vmlinux:
>
> [ ... ]
> 374 ffff8000115f22c0 <__initcall_devlink_init4>:
> 375 ffff8000115f22c4 <__initcall_genl_init4>:
> [ ... ]
>
> The function devlink_init() calls genl_register_family() before the
> generic netlink subsystem is initialized.
>
> As the generic netlink initcall level is set since 2005, it seems that
> was not a problem, but now we have the thermal framework initialized
> at the core_initcall level which creates the generic netlink family
> and sends a notification which leads to a subtle memory corruption
> only detectable when the CONFIG_INIT_ON_ALLOC_DEFAULT_ON option is set
> with the earlycon at init time.
>
> The thermal framework needs to be initialized early in order to begin
> the mitigation as soon as possible. Moving it to postcore_initcall is
> acceptable.
>
> This patch changes the initialization level for the generic netlink
> family to the core_initcall and comes after the netlink protocol
> initialization.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

I confirm, that this change together with the thermal subsystem initcall 
change fixes the issue observed in linux-next for the last few days.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>

> ---
>   net/netlink/genetlink.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
> index 55ee680e9db1..36b8a1909826 100644
> --- a/net/netlink/genetlink.c
> +++ b/net/netlink/genetlink.c
> @@ -1263,7 +1263,7 @@ static int __init genl_init(void)
>   	panic("GENL: Cannot register controller: %d\n", err);
>   }
>   
> -subsys_initcall(genl_init);
> +core_initcall(genl_init);
>   
>   static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
>   			 gfp_t flags)

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

Re: [PATCH] net: genetlink: Move initialization to core_initcall

[Amit Kucheria]

On Wed, Jul 15, 2020 at 1:11 PM Daniel Lezcano
<daniel.lezcano@linaro.org> wrote:
>
> The generic netlink is initialized far after the netlink protocol
> itself at subsys_initcall. The devlink is initialized at the same
> level, but after, as shown by a disassembly of the vmlinux:
>
> [ ... ]
> 374 ffff8000115f22c0 <__initcall_devlink_init4>:
> 375 ffff8000115f22c4 <__initcall_genl_init4>:
> [ ... ]
>
> The function devlink_init() calls genl_register_family() before the
> generic netlink subsystem is initialized.
>
> As the generic netlink initcall level is set since 2005, it seems that
> was not a problem, but now we have the thermal framework initialized
> at the core_initcall level which creates the generic netlink family
> and sends a notification which leads to a subtle memory corruption
> only detectable when the CONFIG_INIT_ON_ALLOC_DEFAULT_ON option is set
> with the earlycon at init time.
>
> The thermal framework needs to be initialized early in order to begin
> the mitigation as soon as possible. Moving it to postcore_initcall is
> acceptable.
>
> This patch changes the initialization level for the generic netlink
> family to the core_initcall and comes after the netlink protocol
> initialization.
>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>


> ---
>  net/netlink/genetlink.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
> index 55ee680e9db1..36b8a1909826 100644
> --- a/net/netlink/genetlink.c
> +++ b/net/netlink/genetlink.c
> @@ -1263,7 +1263,7 @@ static int __init genl_init(void)
>         panic("GENL: Cannot register controller: %d\n", err);
>  }
>
> -subsys_initcall(genl_init);
> +core_initcall(genl_init);
>
>  static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
>                          gfp_t flags)
> --
> 2.17.1
>