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Groups > linux.kernel > #1460055 > unrolled thread

[PATCH 1/4] befs: check allocation_group number before use

Started bySalah Triki <salah.triki@gmail.com>
First post2016-08-11 00:20 +0200
Last post2016-08-12 12:20 +0200
Articles 5 — 2 participants

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  [PATCH 1/4] befs: check allocation_group number before use Salah Triki <salah.triki@gmail.com> - 2016-08-11 00:20 +0200
    Re: [PATCH 1/4] befs: check allocation_group number before use Luis de Bethencourt <luisbg@osg.samsung.com> - 2016-08-11 13:00 +0200
      Re: [PATCH 1/4] befs: check allocation_group number before use Salah Triki <salah.triki@gmail.com> - 2016-08-12 09:30 +0200
        Re: [PATCH 1/4] befs: check allocation_group number before use Luis de Bethencourt <luisbg@osg.samsung.com> - 2016-08-12 11:40 +0200
          Re: [PATCH 1/4] befs: check allocation_group number before use Salah Triki <salah.triki@gmail.com> - 2016-08-12 12:20 +0200

#1460055 — [PATCH 1/4] befs: check allocation_group number before use

FromSalah Triki <salah.triki@gmail.com>
Date2016-08-11 00:20 +0200
Subject[PATCH 1/4] befs: check allocation_group number before use
Message-ID<s4K0W-2GI-7@gated-at.bofh.it>
Check that the allocation group number is not greater or equal to the
number of allocations group in the file system and return BEF_ERR in the
case of error.

Signed-off-by: Salah Triki <salah.triki@gmail.com>
---
 fs/befs/befs.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/befs/befs.h b/fs/befs/befs.h
index 55f3ea2..6daf4c4 100644
--- a/fs/befs/befs.h
+++ b/fs/befs/befs.h
@@ -121,6 +121,11 @@ BEFS_I(const struct inode *inode)
 static inline befs_blocknr_t
 iaddr2blockno(struct super_block *sb, const befs_inode_addr *iaddr)
 {
+	if (iaddr->allocation_group >= BEFS_SB(sb)->num_ags) {
+		befs_error(sb, "BEFS: Invalid allocation group %u, max is %u",
+			   iaddr->allocation_group, BEFS_SB(sb)->num_ags);
+		return BEFS_ERR;
+	}
 	return ((iaddr->allocation_group << BEFS_SB(sb)->ag_shift) +
 		iaddr->start);
 }
-- 
1.9.1

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#1460402

FromLuis de Bethencourt <luisbg@osg.samsung.com>
Date2016-08-11 13:00 +0200
Message-ID<s4VSv-2Iy-25@gated-at.bofh.it>
In reply to#1460055
On 10/08/16 23:12, Salah Triki wrote:
> Check that the allocation group number is not greater or equal to the
> number of allocations group in the file system and return BEF_ERR in the
> case of error.
> 
> Signed-off-by: Salah Triki <salah.triki@gmail.com>
> ---
>  fs/befs/befs.h | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/fs/befs/befs.h b/fs/befs/befs.h
> index 55f3ea2..6daf4c4 100644
> --- a/fs/befs/befs.h
> +++ b/fs/befs/befs.h
> @@ -121,6 +121,11 @@ BEFS_I(const struct inode *inode)
>  static inline befs_blocknr_t
>  iaddr2blockno(struct super_block *sb, const befs_inode_addr *iaddr)
>  {
> +	if (iaddr->allocation_group >= BEFS_SB(sb)->num_ags) {
> +		befs_error(sb, "BEFS: Invalid allocation group %u, max is %u",
> +			   iaddr->allocation_group, BEFS_SB(sb)->num_ags);
> +		return BEFS_ERR;
> +	}
>  	return ((iaddr->allocation_group << BEFS_SB(sb)->ag_shift) +
>  		iaddr->start);
>  }
> 

Hi Salah,

To understand why would we check for this. When can this error happen? I mean,
when can iaddr2blockno() be called with an out of bounds allocation group?

Thanks,
Luis

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#1460980

FromSalah Triki <salah.triki@gmail.com>
Date2016-08-12 09:30 +0200
Message-ID<s5f4J-74l-1@gated-at.bofh.it>
In reply to#1460402
On Thu, Aug 11, 2016 at 11:56:16AM +0100, Luis de Bethencourt wrote:
> On 10/08/16 23:12, Salah Triki wrote:
> > Check that the allocation group number is not greater or equal to the
> > number of allocations group in the file system and return BEF_ERR in the
> > case of error.
> > 
> > Signed-off-by: Salah Triki <salah.triki@gmail.com>
> > ---
> >  fs/befs/befs.h | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/fs/befs/befs.h b/fs/befs/befs.h
> > index 55f3ea2..6daf4c4 100644
> > --- a/fs/befs/befs.h
> > +++ b/fs/befs/befs.h
> > @@ -121,6 +121,11 @@ BEFS_I(const struct inode *inode)
> >  static inline befs_blocknr_t
> >  iaddr2blockno(struct super_block *sb, const befs_inode_addr *iaddr)
> >  {
> > +	if (iaddr->allocation_group >= BEFS_SB(sb)->num_ags) {
> > +		befs_error(sb, "BEFS: Invalid allocation group %u, max is %u",
> > +			   iaddr->allocation_group, BEFS_SB(sb)->num_ags);
> > +		return BEFS_ERR;
> > +	}
> >  	return ((iaddr->allocation_group << BEFS_SB(sb)->ag_shift) +
> >  		iaddr->start);
> >  }
> > 
> 
> Hi Salah,
> 
> To understand why would we check for this. When can this error happen? I mean,
> when can iaddr2blockno() be called with an out of bounds allocation group?
> 
> Thanks,
> Luis

Hi Luis,

allocation group number is set to blockno >> BEFS_SB(sb)->ag_shift by 
blockno2iaddr(), so if ag_shift is not valid, an out of bound may occur. 
By now, thanx to your question ;), I think it's better to check the validity 
of ag_shift when the superblock is loaded.

Nack.

Thanx for the question :)
Salah 

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#1461037

FromLuis de Bethencourt <luisbg@osg.samsung.com>
Date2016-08-12 11:40 +0200
Message-ID<s5h6x-8kl-11@gated-at.bofh.it>
In reply to#1460980
On 12/08/16 08:26, Salah Triki wrote:
> On Thu, Aug 11, 2016 at 11:56:16AM +0100, Luis de Bethencourt wrote:
>> On 10/08/16 23:12, Salah Triki wrote:
>>> Check that the allocation group number is not greater or equal to the
>>> number of allocations group in the file system and return BEF_ERR in the
>>> case of error.
>>>
>>> Signed-off-by: Salah Triki <salah.triki@gmail.com>
>>> ---
>>>  fs/befs/befs.h | 5 +++++
>>>  1 file changed, 5 insertions(+)
>>>
>>> diff --git a/fs/befs/befs.h b/fs/befs/befs.h
>>> index 55f3ea2..6daf4c4 100644
>>> --- a/fs/befs/befs.h
>>> +++ b/fs/befs/befs.h
>>> @@ -121,6 +121,11 @@ BEFS_I(const struct inode *inode)
>>>  static inline befs_blocknr_t
>>>  iaddr2blockno(struct super_block *sb, const befs_inode_addr *iaddr)
>>>  {
>>> +	if (iaddr->allocation_group >= BEFS_SB(sb)->num_ags) {
>>> +		befs_error(sb, "BEFS: Invalid allocation group %u, max is %u",
>>> +			   iaddr->allocation_group, BEFS_SB(sb)->num_ags);
>>> +		return BEFS_ERR;
>>> +	}
>>>  	return ((iaddr->allocation_group << BEFS_SB(sb)->ag_shift) +
>>>  		iaddr->start);
>>>  }
>>>
>>
>> Hi Salah,
>>
>> To understand why would we check for this. When can this error happen? I mean,
>> when can iaddr2blockno() be called with an out of bounds allocation group?
>>
>> Thanks,
>> Luis
> 
> Hi Luis,
> 
> allocation group number is set to blockno >> BEFS_SB(sb)->ag_shift by 
> blockno2iaddr(), so if ag_shift is not valid, an out of bound may occur. 
> By now, thanx to your question ;), I think it's better to check the validity 
> of ag_shift when the superblock is loaded.
> 
> Nack.
> 
> Thanx for the question :)
> Salah 
> 

No problem :)

I will assume the Nack covers patch 1 to 3. Since they are all related.

Enjoy the weekend,
Luis

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#1461063

FromSalah Triki <salah.triki@gmail.com>
Date2016-08-12 12:20 +0200
Message-ID<s5hJg-lu-1@gated-at.bofh.it>
In reply to#1461037
On Fri, Aug 12, 2016 at 10:38:58AM +0100, Luis de Bethencourt wrote:
> On 12/08/16 08:26, Salah Triki wrote:
> > On Thu, Aug 11, 2016 at 11:56:16AM +0100, Luis de Bethencourt wrote:
> >> On 10/08/16 23:12, Salah Triki wrote:
> >>> Check that the allocation group number is not greater or equal to the
> >>> number of allocations group in the file system and return BEF_ERR in the
> >>> case of error.
> >>>
> >>> Signed-off-by: Salah Triki <salah.triki@gmail.com>
> >>> ---
> >>>  fs/befs/befs.h | 5 +++++
> >>>  1 file changed, 5 insertions(+)
> >>>
> >>> diff --git a/fs/befs/befs.h b/fs/befs/befs.h
> >>> index 55f3ea2..6daf4c4 100644
> >>> --- a/fs/befs/befs.h
> >>> +++ b/fs/befs/befs.h
> >>> @@ -121,6 +121,11 @@ BEFS_I(const struct inode *inode)
> >>>  static inline befs_blocknr_t
> >>>  iaddr2blockno(struct super_block *sb, const befs_inode_addr *iaddr)
> >>>  {
> >>> +	if (iaddr->allocation_group >= BEFS_SB(sb)->num_ags) {
> >>> +		befs_error(sb, "BEFS: Invalid allocation group %u, max is %u",
> >>> +			   iaddr->allocation_group, BEFS_SB(sb)->num_ags);
> >>> +		return BEFS_ERR;
> >>> +	}
> >>>  	return ((iaddr->allocation_group << BEFS_SB(sb)->ag_shift) +
> >>>  		iaddr->start);
> >>>  }
> >>>
> >>
> >> Hi Salah,
> >>
> >> To understand why would we check for this. When can this error happen? I mean,
> >> when can iaddr2blockno() be called with an out of bounds allocation group?
> >>
> >> Thanks,
> >> Luis
> > 
> > Hi Luis,
> > 
> > allocation group number is set to blockno >> BEFS_SB(sb)->ag_shift by 
> > blockno2iaddr(), so if ag_shift is not valid, an out of bound may occur. 
> > By now, thanx to your question ;), I think it's better to check the validity 
> > of ag_shift when the superblock is loaded.
> > 
> > Nack.
> > 
> > Thanx for the question :)
> > Salah 
> > 
> 
> No problem :)
> 
> I will assume the Nack covers patch 1 to 3. Since they are all related.
> 
> Enjoy the weekend,
> Luis

You too.
Salah

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