Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[Ari Kauppi]

> On 10.5.2017, at 0.14, Colin Ian King  wrote:
> 
> On 09/05/17 22:03, J . Bruce Fields wrote:
>> On Tue, May 09, 2017 at 05:04:14PM +0300, Dan Carpenter wrote:
>>> On Tue, May 09, 2017 at 02:31:21PM +0100, Colin King wrote:
 diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
 index 1dbf62190bee..c453a1998e00 100644
 --- a/fs/nfsd/nfs4proc.c
 +++ b/fs/nfsd/nfs4proc.c
 @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
 int layout_type)
return NULL;
}
 
 -  if (layout_type >= 32 || !(exp->ex_layout_types & (1 << layout_type))) {
 +  if (layout_type >= LAYOUT_TYPE_MAX ||
 +  !(exp->ex_layout_types & (1 << layout_type))) {
>>> 
>>> The 32 is there to prevent a shift wrapping bug.  The bit test prevents
>>> a buffer overflow so this can't actually overflow.
>> 
>> Yes, looks like a false positive for coverity.
>> 
>>> But this change doesn't hurt and is probably cleaner.
>> 
>> Sure.  Hope it's OK if I just merge this into the previous commit:
> 
> Fine by me.  Colin

Looks good to me.

Thanks,

--
Ari

Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[Ari Kauppi]

> On 10.5.2017, at 0.14, Colin Ian King  wrote:
> 
> On 09/05/17 22:03, J . Bruce Fields wrote:
>> On Tue, May 09, 2017 at 05:04:14PM +0300, Dan Carpenter wrote:
>>> On Tue, May 09, 2017 at 02:31:21PM +0100, Colin King wrote:
 diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
 index 1dbf62190bee..c453a1998e00 100644
 --- a/fs/nfsd/nfs4proc.c
 +++ b/fs/nfsd/nfs4proc.c
 @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
 int layout_type)
return NULL;
}
 
 -  if (layout_type >= 32 || !(exp->ex_layout_types & (1 << layout_type))) {
 +  if (layout_type >= LAYOUT_TYPE_MAX ||
 +  !(exp->ex_layout_types & (1 << layout_type))) {
>>> 
>>> The 32 is there to prevent a shift wrapping bug.  The bit test prevents
>>> a buffer overflow so this can't actually overflow.
>> 
>> Yes, looks like a false positive for coverity.
>> 
>>> But this change doesn't hurt and is probably cleaner.
>> 
>> Sure.  Hope it's OK if I just merge this into the previous commit:
> 
> Fine by me.  Colin

Looks good to me.

Thanks,

--
Ari

Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[Colin Ian King]

On 09/05/17 22:03, J . Bruce Fields wrote:
> On Tue, May 09, 2017 at 05:04:14PM +0300, Dan Carpenter wrote:
>> On Tue, May 09, 2017 at 02:31:21PM +0100, Colin King wrote:
>>> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
>>> index 1dbf62190bee..c453a1998e00 100644
>>> --- a/fs/nfsd/nfs4proc.c
>>> +++ b/fs/nfsd/nfs4proc.c
>>> @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
>>> int layout_type)
>>> return NULL;
>>> }
>>>  
>>> -   if (layout_type >= 32 || !(exp->ex_layout_types & (1 << layout_type))) {
>>> +   if (layout_type >= LAYOUT_TYPE_MAX ||
>>> +   !(exp->ex_layout_types & (1 << layout_type))) {
>>
>> The 32 is there to prevent a shift wrapping bug.  The bit test prevents
>> a buffer overflow so this can't actually overflow.
> 
> Yes, looks like a false positive for coverity.
> 
>> But this change doesn't hurt and is probably cleaner.
> 
> Sure.  Hope it's OK if I just merge this into the previous commit:

Fine by me.  Colin

> 
> --b.
> 
> commit 16b6f81d8ed9
> Author: Ari Kauppi 
> Date:   Fri May 5 16:07:55 2017 -0400
> 
> nfsd: fix undefined behavior in nfsd4_layout_verify
> 
>   UBSAN: Undefined behaviour in fs/nfsd/nfs4proc.c:1262:34
>   shift exponent 128 is too large for 32-bit type 'int'
> 
> Depending on compiler+architecture, this may cause the check for
> layout_type to succeed for overly large values (which seems to be the
> case with amd64). The large value will be later used in de-referencing
> nfsd4_layout_ops for function pointers.
> 
> Reported-by: Jani Tuovila 
> Signed-off-by: Ari Kauppi 
> [colin.k...@canonical.com: use LAYOUT_TYPE_MAX instead of 32]
> Reviewed-by: Dan Carpenter 
> Signed-off-by: J. Bruce Fields 
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index d86031b6ad79..c453a1998e00 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
> int layout_type)
>   return NULL;
>   }
>  
> - if (!(exp->ex_layout_types & (1 << layout_type))) {
> + if (layout_type >= LAYOUT_TYPE_MAX ||
> + !(exp->ex_layout_types & (1 << layout_type))) {
>   dprintk("%s: layout type %d not supported\n",
>   __func__, layout_type);
>   return NULL;
> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
> the body of a message to majord...@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[Colin Ian King]

On 09/05/17 22:03, J . Bruce Fields wrote:
> On Tue, May 09, 2017 at 05:04:14PM +0300, Dan Carpenter wrote:
>> On Tue, May 09, 2017 at 02:31:21PM +0100, Colin King wrote:
>>> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
>>> index 1dbf62190bee..c453a1998e00 100644
>>> --- a/fs/nfsd/nfs4proc.c
>>> +++ b/fs/nfsd/nfs4proc.c
>>> @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
>>> int layout_type)
>>> return NULL;
>>> }
>>>  
>>> -   if (layout_type >= 32 || !(exp->ex_layout_types & (1 << layout_type))) {
>>> +   if (layout_type >= LAYOUT_TYPE_MAX ||
>>> +   !(exp->ex_layout_types & (1 << layout_type))) {
>>
>> The 32 is there to prevent a shift wrapping bug.  The bit test prevents
>> a buffer overflow so this can't actually overflow.
> 
> Yes, looks like a false positive for coverity.
> 
>> But this change doesn't hurt and is probably cleaner.
> 
> Sure.  Hope it's OK if I just merge this into the previous commit:

Fine by me.  Colin

> 
> --b.
> 
> commit 16b6f81d8ed9
> Author: Ari Kauppi 
> Date:   Fri May 5 16:07:55 2017 -0400
> 
> nfsd: fix undefined behavior in nfsd4_layout_verify
> 
>   UBSAN: Undefined behaviour in fs/nfsd/nfs4proc.c:1262:34
>   shift exponent 128 is too large for 32-bit type 'int'
> 
> Depending on compiler+architecture, this may cause the check for
> layout_type to succeed for overly large values (which seems to be the
> case with amd64). The large value will be later used in de-referencing
> nfsd4_layout_ops for function pointers.
> 
> Reported-by: Jani Tuovila 
> Signed-off-by: Ari Kauppi 
> [colin.k...@canonical.com: use LAYOUT_TYPE_MAX instead of 32]
> Reviewed-by: Dan Carpenter 
> Signed-off-by: J. Bruce Fields 
> 
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index d86031b6ad79..c453a1998e00 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
> int layout_type)
>   return NULL;
>   }
>  
> - if (!(exp->ex_layout_types & (1 << layout_type))) {
> + if (layout_type >= LAYOUT_TYPE_MAX ||
> + !(exp->ex_layout_types & (1 << layout_type))) {
>   dprintk("%s: layout type %d not supported\n",
>   __func__, layout_type);
>   return NULL;
> --
> To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in
> the body of a message to majord...@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[J . Bruce Fields]

On Tue, May 09, 2017 at 05:04:14PM +0300, Dan Carpenter wrote:
> On Tue, May 09, 2017 at 02:31:21PM +0100, Colin King wrote:
> > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> > index 1dbf62190bee..c453a1998e00 100644
> > --- a/fs/nfsd/nfs4proc.c
> > +++ b/fs/nfsd/nfs4proc.c
> > @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
> > int layout_type)
> > return NULL;
> > }
> >  
> > -   if (layout_type >= 32 || !(exp->ex_layout_types & (1 << layout_type))) {
> > +   if (layout_type >= LAYOUT_TYPE_MAX ||
> > +   !(exp->ex_layout_types & (1 << layout_type))) {
> 
> The 32 is there to prevent a shift wrapping bug.  The bit test prevents
> a buffer overflow so this can't actually overflow.

Yes, looks like a false positive for coverity.

> But this change doesn't hurt and is probably cleaner.

Sure.  Hope it's OK if I just merge this into the previous commit:

--b.

commit 16b6f81d8ed9
Author: Ari Kauppi 
Date:   Fri May 5 16:07:55 2017 -0400

nfsd: fix undefined behavior in nfsd4_layout_verify

  UBSAN: Undefined behaviour in fs/nfsd/nfs4proc.c:1262:34
  shift exponent 128 is too large for 32-bit type 'int'

Depending on compiler+architecture, this may cause the check for
layout_type to succeed for overly large values (which seems to be the
case with amd64). The large value will be later used in de-referencing
nfsd4_layout_ops for function pointers.

Reported-by: Jani Tuovila 
Signed-off-by: Ari Kauppi 
[colin.k...@canonical.com: use LAYOUT_TYPE_MAX instead of 32]
Reviewed-by: Dan Carpenter 
Signed-off-by: J. Bruce Fields 

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index d86031b6ad79..c453a1998e00 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned int 
layout_type)
return NULL;
}
 
-   if (!(exp->ex_layout_types & (1 << layout_type))) {
+   if (layout_type >= LAYOUT_TYPE_MAX ||
+   !(exp->ex_layout_types & (1 << layout_type))) {
dprintk("%s: layout type %d not supported\n",
__func__, layout_type);
return NULL;

Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[J . Bruce Fields]

On Tue, May 09, 2017 at 05:04:14PM +0300, Dan Carpenter wrote:
> On Tue, May 09, 2017 at 02:31:21PM +0100, Colin King wrote:
> > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> > index 1dbf62190bee..c453a1998e00 100644
> > --- a/fs/nfsd/nfs4proc.c
> > +++ b/fs/nfsd/nfs4proc.c
> > @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
> > int layout_type)
> > return NULL;
> > }
> >  
> > -   if (layout_type >= 32 || !(exp->ex_layout_types & (1 << layout_type))) {
> > +   if (layout_type >= LAYOUT_TYPE_MAX ||
> > +   !(exp->ex_layout_types & (1 << layout_type))) {
> 
> The 32 is there to prevent a shift wrapping bug.  The bit test prevents
> a buffer overflow so this can't actually overflow.

Yes, looks like a false positive for coverity.

> But this change doesn't hurt and is probably cleaner.

Sure.  Hope it's OK if I just merge this into the previous commit:

--b.

commit 16b6f81d8ed9
Author: Ari Kauppi 
Date:   Fri May 5 16:07:55 2017 -0400

nfsd: fix undefined behavior in nfsd4_layout_verify

  UBSAN: Undefined behaviour in fs/nfsd/nfs4proc.c:1262:34
  shift exponent 128 is too large for 32-bit type 'int'

Depending on compiler+architecture, this may cause the check for
layout_type to succeed for overly large values (which seems to be the
case with amd64). The large value will be later used in de-referencing
nfsd4_layout_ops for function pointers.

Reported-by: Jani Tuovila 
Signed-off-by: Ari Kauppi 
[colin.k...@canonical.com: use LAYOUT_TYPE_MAX instead of 32]
Reviewed-by: Dan Carpenter 
Signed-off-by: J. Bruce Fields 

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index d86031b6ad79..c453a1998e00 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned int 
layout_type)
return NULL;
}
 
-   if (!(exp->ex_layout_types & (1 << layout_type))) {
+   if (layout_type >= LAYOUT_TYPE_MAX ||
+   !(exp->ex_layout_types & (1 << layout_type))) {
dprintk("%s: layout type %d not supported\n",
__func__, layout_type);
return NULL;

Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[Christoph Hellwig]

Looks fine,

Reviewed-by: Christoph Hellwig 

Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[Christoph Hellwig]

Looks fine,

Reviewed-by: Christoph Hellwig 

Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[Dan Carpenter]

On Tue, May 09, 2017 at 02:31:21PM +0100, Colin King wrote:
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 1dbf62190bee..c453a1998e00 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
> int layout_type)
>   return NULL;
>   }
>  
> - if (layout_type >= 32 || !(exp->ex_layout_types & (1 << layout_type))) {
> + if (layout_type >= LAYOUT_TYPE_MAX ||
> + !(exp->ex_layout_types & (1 << layout_type))) {

The 32 is there to prevent a shift wrapping bug.  The bit test prevents
a buffer overflow so this can't actually overflow.  But this change
doesn't hurt and is probably cleaner.

exp->ex_layout_types  is set in nfsd4_setup_layout_type().

regards,
dan carpenter

Re: [PATCH] nfsd: avoid out of bounds read on array nfsd4_layout_ops

[Dan Carpenter]

On Tue, May 09, 2017 at 02:31:21PM +0100, Colin King wrote:
> diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> index 1dbf62190bee..c453a1998e00 100644
> --- a/fs/nfsd/nfs4proc.c
> +++ b/fs/nfsd/nfs4proc.c
> @@ -1259,7 +1259,8 @@ nfsd4_layout_verify(struct svc_export *exp, unsigned 
> int layout_type)
>   return NULL;
>   }
>  
> - if (layout_type >= 32 || !(exp->ex_layout_types & (1 << layout_type))) {
> + if (layout_type >= LAYOUT_TYPE_MAX ||
> + !(exp->ex_layout_types & (1 << layout_type))) {

The 32 is there to prevent a shift wrapping bug.  The bit test prevents
a buffer overflow so this can't actually overflow.  But this change
doesn't hurt and is probably cleaner.

exp->ex_layout_types  is set in nfsd4_setup_layout_type().

regards,
dan carpenter