From: duoming@zju.edu.cn
To: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] mwifiex: fix sleep in atomic context bugs caused by dev_coredumpv
Date: Mon, 23 May 2022 16:03:32 +0800 (GMT+08:00) [thread overview]
Message-ID: <6d8c70c0.2b1f1.180eff156be.Coremail.duoming@zju.edu.cn> (raw)
Hello,
On Mon, 23 May 2022 08:31:46 +0200 Greg KH wrote:
> > There are sleep in atomic context bugs when uploading device dump
> > data in mwifiex. The root cause is that dev_coredumpv could not
> > be used in atomic contexts, because it calls dev_set_name which
> > include operations that may sleep. The call tree shows execution
> > paths that could lead to bugs:
> >
> > (Interrupt context)
> > fw_dump_timer_fn
> > mwifiex_upload_device_dump
> > dev_coredumpv(..., GFP_KERNEL)
> > dev_coredumpm()
> > kzalloc(sizeof(*devcd), gfp); //may sleep
> > dev_set_name
> > kobject_set_name_vargs
> > kvasprintf_const(GFP_KERNEL, ...); //may sleep
> > kstrdup(s, GFP_KERNEL); //may sleep
> >
> > In order to let dev_coredumpv support atomic contexts, this patch
> > changes the gfp_t parameter of kvasprintf_const and kstrdup in
> > kobject_set_name_vargs from GFP_KERNEL to GFP_ATOMIC. What's more,
> > In order to mitigate bug, this patch changes the gfp_t parameter
> > of dev_coredumpv from GFP_KERNEL to GFP_ATOMIC.
> >
> > Fixes: 57670ee882d4 ("mwifiex: device dump support via devcoredump framework")
> > Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
> > ---
> > Changes in v3:
> > - Let dev_coredumpv support atomic contexts.
> >
> > drivers/net/wireless/marvell/mwifiex/main.c | 2 +-
> > lib/kobject.c | 4 ++--
> > 2 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c
> > index ace7371c477..258906920a2 100644
> > --- a/drivers/net/wireless/marvell/mwifiex/main.c
> > +++ b/drivers/net/wireless/marvell/mwifiex/main.c
> > @@ -1116,7 +1116,7 @@ void mwifiex_upload_device_dump(struct mwifiex_adapter *adapter)
> > mwifiex_dbg(adapter, MSG,
> > "== mwifiex dump information to /sys/class/devcoredump start\n");
> > dev_coredumpv(adapter->dev, adapter->devdump_data, adapter->devdump_len,
> > - GFP_KERNEL);
> > + GFP_ATOMIC);
> > mwifiex_dbg(adapter, MSG,
> > "== mwifiex dump information to /sys/class/devcoredump end\n");
> >
> > diff --git a/lib/kobject.c b/lib/kobject.c
> > index 5f0e71ab292..7672c54944c 100644
> > --- a/lib/kobject.c
> > +++ b/lib/kobject.c
> > @@ -254,7 +254,7 @@ int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
> > if (kobj->name && !fmt)
> > return 0;
> >
> > - s = kvasprintf_const(GFP_KERNEL, fmt, vargs);
> > + s = kvasprintf_const(GFP_ATOMIC, fmt, vargs);
> > if (!s)
> > return -ENOMEM;
> >
> > @@ -267,7 +267,7 @@ int kobject_set_name_vargs(struct kobject *kobj, const char *fmt,
> > if (strchr(s, '/')) {
> > char *t;
> >
> > - t = kstrdup(s, GFP_KERNEL);
> > + t = kstrdup(s, GFP_ATOMIC);
> > kfree_const(s);
> > if (!t)
> > return -ENOMEM;
>
> Please no, you are hurting the whole kernel because of one odd user.
> Please do not make these calls under atomic context.
Thanks for your time and suggestions. I will remove the gfp_t parameter of dev_coredumpv
in order to show it could not be used in atomic context.
Best Regards,
Duoming Zhou
next reply other threads:[~2022-05-23 8:03 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-23 8:03 duoming [this message]
-- strict thread matches above, loose matches on Subject: below --
2022-05-23 5:28 [PATCH v3] mwifiex: fix sleep in atomic context bugs caused by dev_coredumpv Duoming Zhou
2022-05-23 6:31 ` Greg KH
[not found] ` <41a266af.2abb6.180efa8594d.Coremail.duoming@zju.edu.cn>
2022-05-23 11:31 ` Kalle Valo
2022-05-23 13:41 ` Greg KH
2022-05-23 16:27 ` Kalle Valo
2022-05-23 13:43 ` Johannes Berg
2022-05-23 14:20 ` Eric W. Biederman
2022-05-23 15:58 ` duoming
2022-05-23 16:31 ` Kalle Valo
2022-05-24 2:08 ` duoming
2022-05-23 19:42 ` Brian Norris
2022-05-24 1:54 ` duoming
2022-05-23 17:55 ` Brian Norris
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