[PATCH v2 0/2] staging: r8188eu: Use kzalloc() with GFP_ATOMIC in atomic context

[PATCH v2 0/2] staging: r8188eu: Use kzalloc() with GFP_ATOMIC in atomic context

[Fabio M. De Francesco]

Use the GFP_ATOMIC flag of kzalloc() in two memory allocation in rtw_set_key().
This function is not allowed to sleep because it executes in atomic context. With
the GFP_ATOMIC type flag, the allocation is high priority and cannot sleep.

This issue is detected by Smatch which emits the following warning:
drivers/staging/r8188eu/core/rtw_mlme.c:1603 rtw_set_key() warn: sleeping in atomic context

Before the above-mentioned changes, checkpatch.pl reports the following issues:

CHECK: Prefer kzalloc(sizeof(*pcmd)...) over kzalloc(sizeof(struct cmd_obj)...)
+       pcmd = kzalloc(sizeof(struct cmd_obj), GFP_ATOMIC);

CHECK: Prefer kzalloc(sizeof(*psetkeyparm)...) over kzalloc(sizeof(struct setkey_parm)...)
+       psetkeyparm = kzalloc(sizeof(struct setkey_parm), GFP_ATOMIC).

According to the above "CHECK[S]", use the preferred style in the two kzalloc().

Changes from v1: Split one patch into two according to a requirement by
Greg Kroah-Hartman.

Fabio M. De Francesco (2):
  staging: r8188eu: Use size of dereferenced pointers in kzalloc()
  staging: r8188eu: Use kzalloc() with GFP_ATOMIC in atomic context

 drivers/staging/r8188eu/core/rtw_mlme.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

-- 
2.34.1

[PATCH v2 1/2] staging: r8188eu: Use sizeof dereferenced pointer in kzalloc()

[Fabio M. De Francesco]

checkpatch.pl emits the following warning:

CHECK: Prefer kzalloc(sizeof(*pcmd)...) over kzalloc(sizeof(struct cmd_obj)...)
+       pcmd = kzalloc(sizeof(struct cmd_obj), GFP_KERNEL);

CHECK: Prefer kzalloc(sizeof(*psetkeyparm)...) over kzalloc(sizeof(struct setkey_parm)...)
+       psetkeyparm = kzalloc(sizeof(struct setkey_parm), GFP_KERNEL).

According to the above "CHECK[S]", use the preferred style in the two kzalloc()
of rtw_set_key().

Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---

 drivers/staging/r8188eu/core/rtw_mlme.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_mlme.c b/drivers/staging/r8188eu/core/rtw_mlme.c
index 038bddc361c3..f5b2df72e0f4 100644
--- a/drivers/staging/r8188eu/core/rtw_mlme.c
+++ b/drivers/staging/r8188eu/core/rtw_mlme.c
@@ -1600,12 +1600,12 @@ int rtw_set_key(struct adapter *adapter, struct security_priv *psecuritypriv, in
 	struct mlme_priv		*pmlmepriv = &adapter->mlmepriv;
 	int	res = _SUCCESS;
 
-	pcmd = kzalloc(sizeof(struct cmd_obj), GFP_KERNEL);
+	pcmd = kzalloc(sizeof(*pcmd), GFP_KERNEL);
 	if (!pcmd) {
 		res = _FAIL;  /* try again */
 		goto exit;
 	}
-	psetkeyparm = kzalloc(sizeof(struct setkey_parm), GFP_KERNEL);
+	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_KERNEL);
 	if (!psetkeyparm) {
 		kfree(pcmd);
 		res = _FAIL;
-- 
2.34.1

[PATCH v2 2/2] staging: r8188eu: Use kzalloc() with GFP_ATOMIC in atomic context

[Fabio M. De Francesco]

Use the GFP_ATOMIC flag of kzalloc() with two memory allocation in rtw_set_key() 
because it is not allowed to sleep while it executes in atomic context.

With the GFP_ATOMIC type flag, the allocation is high priority and thus it 
cannot sleep.

This issue is detected by Smatch which emits the following warning:

"drivers/staging/r8188eu/core/rtw_mlme.c:1603 rtw_set_key() warn: sleeping in atomic context".

Fixes: 79f712ea994d ("staging: r8188eu: Remove wrappers for kalloc() and kzalloc()")
Fixes: 15865124feed ("staging: r8188eu: introduce new core dir for RTL8188eu driver")
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
---
 drivers/staging/r8188eu/core/rtw_mlme.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/r8188eu/core/rtw_mlme.c b/drivers/staging/r8188eu/core/rtw_mlme.c
index f5b2df72e0f4..860835e29b79 100644
--- a/drivers/staging/r8188eu/core/rtw_mlme.c
+++ b/drivers/staging/r8188eu/core/rtw_mlme.c
@@ -1600,12 +1600,12 @@ int rtw_set_key(struct adapter *adapter, struct security_priv *psecuritypriv, in
 	struct mlme_priv		*pmlmepriv = &adapter->mlmepriv;
 	int	res = _SUCCESS;
 
-	pcmd = kzalloc(sizeof(*pcmd), GFP_KERNEL);
+	pcmd = kzalloc(sizeof(*pcmd), GFP_ATOMIC);
 	if (!pcmd) {
 		res = _FAIL;  /* try again */
 		goto exit;
 	}
-	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_KERNEL);
+	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_ATOMIC);
 	if (!psetkeyparm) {
 		kfree(pcmd);
 		res = _FAIL;
-- 
2.34.1

Re: [PATCH v2 2/2] staging: r8188eu: Use kzalloc() with GFP_ATOMIC in atomic context

[Greg Kroah-Hartman]

On Tue, Feb 08, 2022 at 07:04:26PM +0100, Fabio M. De Francesco wrote:
> Use the GFP_ATOMIC flag of kzalloc() with two memory allocation in rtw_set_key() 
> because it is not allowed to sleep while it executes in atomic context.
> 
> With the GFP_ATOMIC type flag, the allocation is high priority and thus it 
> cannot sleep.
> 
> This issue is detected by Smatch which emits the following warning:
> 
> "drivers/staging/r8188eu/core/rtw_mlme.c:1603 rtw_set_key() warn: sleeping in atomic context".
> 
> Fixes: 79f712ea994d ("staging: r8188eu: Remove wrappers for kalloc() and kzalloc()")
> Fixes: 15865124feed ("staging: r8188eu: introduce new core dir for RTL8188eu driver")
> Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> ---
>  drivers/staging/r8188eu/core/rtw_mlme.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/staging/r8188eu/core/rtw_mlme.c b/drivers/staging/r8188eu/core/rtw_mlme.c
> index f5b2df72e0f4..860835e29b79 100644
> --- a/drivers/staging/r8188eu/core/rtw_mlme.c
> +++ b/drivers/staging/r8188eu/core/rtw_mlme.c
> @@ -1600,12 +1600,12 @@ int rtw_set_key(struct adapter *adapter, struct security_priv *psecuritypriv, in
>  	struct mlme_priv		*pmlmepriv = &adapter->mlmepriv;
>  	int	res = _SUCCESS;
>  
> -	pcmd = kzalloc(sizeof(*pcmd), GFP_KERNEL);
> +	pcmd = kzalloc(sizeof(*pcmd), GFP_ATOMIC);
>  	if (!pcmd) {
>  		res = _FAIL;  /* try again */
>  		goto exit;
>  	}
> -	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_KERNEL);
> +	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_ATOMIC);
>  	if (!psetkeyparm) {
>  		kfree(pcmd);
>  		res = _FAIL;
> -- 
> 2.34.1

What code path is calling this in atomic context?

thanks,

greg k-h

Re: [PATCH v2 2/2] staging: r8188eu: Use kzalloc() with GFP_ATOMIC in atomic context

[Fabio M. De Francesco]

On marted? 15 febbraio 2022 17:10:12 CET Greg Kroah-Hartman wrote:
> On Tue, Feb 08, 2022 at 07:04:26PM +0100, Fabio M. De Francesco wrote:
> > Use the GFP_ATOMIC flag of kzalloc() with two memory allocation in rtw_set_key() 
> > because it is not allowed to sleep while it executes in atomic context.
> > 
> > With the GFP_ATOMIC type flag, the allocation is high priority and thus it 
> > cannot sleep.
> > 
> > This issue is detected by Smatch which emits the following warning:
> > 
> > "drivers/staging/r8188eu/core/rtw_mlme.c:1603 rtw_set_key() warn: sleeping in atomic context".
> > 
> > Fixes: 79f712ea994d ("staging: r8188eu: Remove wrappers for kalloc() and kzalloc()")
> > Fixes: 15865124feed ("staging: r8188eu: introduce new core dir for RTL8188eu driver")
> > Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
> > ---
> >  drivers/staging/r8188eu/core/rtw_mlme.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/staging/r8188eu/core/rtw_mlme.c b/drivers/staging/r8188eu/core/rtw_mlme.c
> > index f5b2df72e0f4..860835e29b79 100644
> > --- a/drivers/staging/r8188eu/core/rtw_mlme.c
> > +++ b/drivers/staging/r8188eu/core/rtw_mlme.c
> > @@ -1600,12 +1600,12 @@ int rtw_set_key(struct adapter *adapter, struct security_priv *psecuritypriv, in
> >  	struct mlme_priv		*pmlmepriv = &adapter->mlmepriv;
> >  	int	res = _SUCCESS;
> >  
> > -	pcmd = kzalloc(sizeof(*pcmd), GFP_KERNEL);
> > +	pcmd = kzalloc(sizeof(*pcmd), GFP_ATOMIC);
> >  	if (!pcmd) {
> >  		res = _FAIL;  /* try again */
> >  		goto exit;
> >  	}
> > -	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_KERNEL);
> > +	psetkeyparm = kzalloc(sizeof(*psetkeyparm), GFP_ATOMIC);
> >  	if (!psetkeyparm) {
> >  		kfree(pcmd);
> >  		res = _FAIL;
> > -- 
> > 2.34.1
> 
> What code path is calling this in atomic context?
> 
> thanks,
> 
> greg k-h
> 
I blindly trusted Smatch and didn't check properly :(

Now I'm pretty sure that all(?) the code paths that lead to those kzalloc() do 
not call rtw_set_key() in atomic context.

The only calls chain that seemed to call rtw_set_key() in atomic context was 
rtw_set_key() <- ips_leave() <- _rtw_pwr_wakeup() <- rtw_set_802_11_disassociate() 
but Smatch (and I) missed that, immediately before calling ips_leave(), an 'if'
condition makes _rtw_pwr_wakeup() exit and return to rtw_set_802_11_disassociate().

Therefore, please drop this patch.

Thanks,

Fabio M. De Francesco