[PATCH net] net: wwan: iosm: Call mutex_init before locking it

[PATCH net] net: wwan: iosm: Call mutex_init before locking it

[Maxim Mikityanskiy]

wwan_register_ops calls wwan_create_default_link, which ends up in the
ipc_wwan_newlink callback that locks ipc_wwan->if_mutex. However, this
mutex is not yet initialized by that point. Fix it by moving mutex_init
above the wwan_register_ops call. This also makes the order of
operations in ipc_wwan_init symmetric to ipc_wwan_deinit.

Fixes: 83068395bbfc ("net: iosm: create default link via WWAN core")
Signed-off-by: Maxim Mikityanskiy <maxtram95@gmail.com>
---
 drivers/net/wwan/iosm/iosm_ipc_wwan.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wwan/iosm/iosm_ipc_wwan.c b/drivers/net/wwan/iosm/iosm_ipc_wwan.c
index 27151148c782..4712f01a7e33 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_wwan.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_wwan.c
@@ -323,15 +323,16 @@ struct iosm_wwan *ipc_wwan_init(struct iosm_imem *ipc_imem, struct device *dev)
 	ipc_wwan->dev = dev;
 	ipc_wwan->ipc_imem = ipc_imem;
 
+	mutex_init(&ipc_wwan->if_mutex);
+
 	/* WWAN core will create a netdev for the default IP MUX channel */
 	if (wwan_register_ops(ipc_wwan->dev, &iosm_wwan_ops, ipc_wwan,
 			      IP_MUX_SESSION_DEFAULT)) {
+		mutex_destroy(&ipc_wwan->if_mutex);
 		kfree(ipc_wwan);
 		return NULL;
 	}
 
-	mutex_init(&ipc_wwan->if_mutex);
-
 	return ipc_wwan;
 }
 
-- 
2.37.3

RE: [PATCH net] net: wwan: iosm: Call mutex_init before locking it

[Kumar, M Chetan]

> -----Original Message-----
> From: Maxim Mikityanskiy <maxtram95@gmail.com>
> Sent: Saturday, October 1, 2022 4:27 PM
> To: Kumar, M Chetan <m.chetan.kumar@intel.com>; linuxwwan
> <linuxwwan@intel.com>
> Cc: Loic Poulain <loic.poulain@linaro.org>; Sergey Ryazanov
> <ryazanov.s.a@gmail.com>; Johannes Berg <johannes@sipsolutions.net>;
> David S. Miller <davem@davemloft.net>; Eric Dumazet
> <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni
> <pabeni@redhat.com>; netdev@vger.kernel.org; Maxim Mikityanskiy
> <maxtram95@gmail.com>
> Subject: [PATCH net] net: wwan: iosm: Call mutex_init before locking it
> 
> wwan_register_ops calls wwan_create_default_link, which ends up in the
> ipc_wwan_newlink callback that locks ipc_wwan->if_mutex. However, this
> mutex is not yet initialized by that point. Fix it by moving mutex_init above
> the wwan_register_ops call. This also makes the order of operations in
> ipc_wwan_init symmetric to ipc_wwan_deinit.
> 
> Fixes: 83068395bbfc ("net: iosm: create default link via WWAN core")
> Signed-off-by: Maxim Mikityanskiy <maxtram95@gmail.com>
> ---
>  drivers/net/wwan/iosm/iosm_ipc_wwan.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wwan/iosm/iosm_ipc_wwan.c
> b/drivers/net/wwan/iosm/iosm_ipc_wwan.c
> index 27151148c782..4712f01a7e33 100644
> --- a/drivers/net/wwan/iosm/iosm_ipc_wwan.c
> +++ b/drivers/net/wwan/iosm/iosm_ipc_wwan.c
> @@ -323,15 +323,16 @@ struct iosm_wwan *ipc_wwan_init(struct
> iosm_imem *ipc_imem, struct device *dev)
>  	ipc_wwan->dev = dev;
>  	ipc_wwan->ipc_imem = ipc_imem;
> 
> +	mutex_init(&ipc_wwan->if_mutex);
> +
>  	/* WWAN core will create a netdev for the default IP MUX channel */
>  	if (wwan_register_ops(ipc_wwan->dev, &iosm_wwan_ops,
> ipc_wwan,
>  			      IP_MUX_SESSION_DEFAULT)) {
> +		mutex_destroy(&ipc_wwan->if_mutex);
>  		kfree(ipc_wwan);
>  		return NULL;
>  	}
> 
> -	mutex_init(&ipc_wwan->if_mutex);
> -
>  	return ipc_wwan;
>  }

Reviewed-by: M Chetan Kumar <m.chetan.kumar@intel.com>

Re: [PATCH net] net: wwan: iosm: Call mutex_init before locking it

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Sat,  1 Oct 2022 13:57:13 +0300 you wrote:
> wwan_register_ops calls wwan_create_default_link, which ends up in the
> ipc_wwan_newlink callback that locks ipc_wwan->if_mutex. However, this
> mutex is not yet initialized by that point. Fix it by moving mutex_init
> above the wwan_register_ops call. This also makes the order of
> operations in ipc_wwan_init symmetric to ipc_wwan_deinit.
> 
> Fixes: 83068395bbfc ("net: iosm: create default link via WWAN core")
> Signed-off-by: Maxim Mikityanskiy <maxtram95@gmail.com>
> 
> [...]

Here is the summary with links:
  - [net] net: wwan: iosm: Call mutex_init before locking it
    https://git.kernel.org/netdev/net/c/ba0fbdb95da5

You are awesome, thank you!
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