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[PATCH] xfs: do not call xfs_buf_hash_destroy on a NULL pag

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  [PATCH] xfs: do not call xfs_buf_hash_destroy on a NULL pag Colin King <colin.king@canonical.com> - 2017-01-20 15:30 +0100
    Re: [PATCH] xfs: do not call xfs_buf_hash_destroy on a NULL pag "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-01-20 17:40 +0100
    Re: [PATCH] xfs: do not call xfs_buf_hash_destroy on a NULL pag Eric Sandeen <sandeen@sandeen.net> - 2017-01-20 20:40 +0100
      Re: [PATCH] xfs: do not call xfs_buf_hash_destroy on a NULL pag "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-01-20 21:50 +0100
        Re: [PATCH] xfs: do not call xfs_buf_hash_destroy on a NULL pag Colin Ian King <colin.king@canonical.com> - 2017-01-21 00:10 +0100
          Re: [PATCH] xfs: do not call xfs_buf_hash_destroy on a NULL pag Bill O'Donnell <billodo@redhat.com> - 2017-01-24 16:10 +0100
            Re: [PATCH] xfs: do not call xfs_buf_hash_destroy on a NULL pag "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-01-24 19:40 +0100

#1563643 — [PATCH] xfs: do not call xfs_buf_hash_destroy on a NULL pag

From: Colin Ian King <colin.king@canonical.com>

If pag cannot be allocated, the current error exit path will trip
a null pointer deference error when calling xfs_buf_hash_destroy
with a null pag.  Fix this by adding a new error exit lable and
jumping to this, avoiding the hash destroy and unnecessary kmem_free
on pag.

Fixes CoverityScan CID#1397628 ("Dereference after null check")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 fs/xfs/xfs_mount.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 9b9540d..4e66cd19 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -207,7 +207,7 @@ xfs_initialize_perag(
 
 		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
 		if (!pag)
-			goto out_unwind;
+			goto out_unwind_pags;
 		pag->pag_agno = index;
 		pag->pag_mount = mp;
 		spin_lock_init(&pag->pag_ici_lock);
@@ -242,6 +242,7 @@ xfs_initialize_perag(
 out_unwind:
 	xfs_buf_hash_destroy(pag);
 	kmem_free(pag);
+out_unwind_pags:
 	for (; index > first_initialised; index--) {
 		pag = radix_tree_delete(&mp->m_perag_tree, index);
 		xfs_buf_hash_destroy(pag);
-- 
2.10.2

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#1563764

On Fri, Jan 20, 2017 at 02:26:42PM +0000, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> If pag cannot be allocated, the current error exit path will trip
> a null pointer deference error when calling xfs_buf_hash_destroy
> with a null pag.  Fix this by adding a new error exit lable and
> jumping to this, avoiding the hash destroy and unnecessary kmem_free
> on pag.
> 
> Fixes CoverityScan CID#1397628 ("Dereference after null check")
> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

Applied, thanks.

--D

> ---
>  fs/xfs/xfs_mount.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 9b9540d..4e66cd19 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -207,7 +207,7 @@ xfs_initialize_perag(
>  
>  		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
>  		if (!pag)
> -			goto out_unwind;
> +			goto out_unwind_pags;
>  		pag->pag_agno = index;
>  		pag->pag_mount = mp;
>  		spin_lock_init(&pag->pag_ici_lock);
> @@ -242,6 +242,7 @@ xfs_initialize_perag(
>  out_unwind:
>  	xfs_buf_hash_destroy(pag);
>  	kmem_free(pag);
> +out_unwind_pags:
>  	for (; index > first_initialised; index--) {
>  		pag = radix_tree_delete(&mp->m_perag_tree, index);
>  		xfs_buf_hash_destroy(pag);
> -- 
> 2.10.2
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

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#1563880

On 1/20/17 8:26 AM, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> If pag cannot be allocated, the current error exit path will trip
> a null pointer deference error when calling xfs_buf_hash_destroy
> with a null pag.  Fix this by adding a new error exit lable and
> jumping to this, avoiding the hash destroy and unnecessary kmem_free
> on pag.
> 
> Fixes CoverityScan CID#1397628 ("Dereference after null check")
> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Hm, I think this leaves the code with issues.

> ---
>  fs/xfs/xfs_mount.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> index 9b9540d..4e66cd19 100644
> --- a/fs/xfs/xfs_mount.c
> +++ b/fs/xfs/xfs_mount.c
> @@ -207,7 +207,7 @@ xfs_initialize_perag(
>  
>  		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
>  		if (!pag)
> -			goto out_unwind;
> +			goto out_unwind_pags;

So let's say we got to index == 3 at the top of the loop, and
this fails.

We succeeded in initializing 0, 1, and 2, but 3 failed.

So we go to out_unwind_pags with index == 3...

>  		pag->pag_agno = index;
>  		pag->pag_mount = mp;
>  		spin_lock_init(&pag->pag_ici_lock);
> @@ -242,6 +242,7 @@ xfs_initialize_perag(
>  out_unwind:
>  	xfs_buf_hash_destroy(pag);
>  	kmem_free(pag);
> +out_unwind_pags:

... where index == 3, and:

>  	for (; index > first_initialised; index--) {
>  		pag = radix_tree_delete(&mp->m_perag_tree, index);

this should fail, because it never got inserted, and...

>  		xfs_buf_hash_destroy(pag);

this still tries to destroy a NULL pag, no?

There also seems to be an existing issue w/the code where ag 0 is
never torn down in the error case, because first_initialized doesn't
stay set to 0:

                if (!first_initialised)
                        first_initialised = index;

And we don't even tear down ag 1, because:

>  	for (; index > first_initialised; index--) {
>  		pag = radix_tree_delete(&mp->m_perag_tree, index);

when the loop reaches the first initialized AG, it stops.

So we seem to always leak at least 2 if we managed to get far enough
to initialize them.

-Eric

> 

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#1563907

On Fri, Jan 20, 2017 at 01:26:12PM -0600, Eric Sandeen wrote:
> On 1/20/17 8:26 AM, Colin King wrote:
> > From: Colin Ian King <colin.king@canonical.com>
> > 
> > If pag cannot be allocated, the current error exit path will trip
> > a null pointer deference error when calling xfs_buf_hash_destroy
> > with a null pag.  Fix this by adding a new error exit lable and
> > jumping to this, avoiding the hash destroy and unnecessary kmem_free
> > on pag.
> > 
> > Fixes CoverityScan CID#1397628 ("Dereference after null check")
> > 
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> 
> Hm, I think this leaves the code with issues.
> 
> > ---
> >  fs/xfs/xfs_mount.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> > index 9b9540d..4e66cd19 100644
> > --- a/fs/xfs/xfs_mount.c
> > +++ b/fs/xfs/xfs_mount.c
> > @@ -207,7 +207,7 @@ xfs_initialize_perag(
> >  
> >  		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
> >  		if (!pag)
> > -			goto out_unwind;
> > +			goto out_unwind_pags;
> 
> So let's say we got to index == 3 at the top of the loop, and
> this fails.
> 
> We succeeded in initializing 0, 1, and 2, but 3 failed.
> 
> So we go to out_unwind_pags with index == 3...
> 
> >  		pag->pag_agno = index;
> >  		pag->pag_mount = mp;
> >  		spin_lock_init(&pag->pag_ici_lock);
> > @@ -242,6 +242,7 @@ xfs_initialize_perag(
> >  out_unwind:
> >  	xfs_buf_hash_destroy(pag);
> >  	kmem_free(pag);
> > +out_unwind_pags:
> 
> ... where index == 3, and:
> 
> >  	for (; index > first_initialised; index--) {
> >  		pag = radix_tree_delete(&mp->m_perag_tree, index);
> 
> this should fail, because it never got inserted, and...
> 
> >  		xfs_buf_hash_destroy(pag);
> 
> this still tries to destroy a NULL pag, no?
> 
> There also seems to be an existing issue w/the code where ag 0 is
> never torn down in the error case, because first_initialized doesn't
> stay set to 0:
> 
>                 if (!first_initialised)
>                         first_initialised = index;
> 
> And we don't even tear down ag 1, because:
> 
> >  	for (; index > first_initialised; index--) {
> >  		pag = radix_tree_delete(&mp->m_perag_tree, index);
> 
> when the loop reaches the first initialized AG, it stops.
> 
> So we seem to always leak at least 2 if we managed to get far enough
> to initialize them.

Ugh, yeah, the the whole error exit from that function is fubar...
Anyone want to clean this up?

--D

> 
> -Eric
> 
> > 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

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#1563986

On 20/01/17 20:47, Darrick J. Wong wrote:
> On Fri, Jan 20, 2017 at 01:26:12PM -0600, Eric Sandeen wrote:
>> On 1/20/17 8:26 AM, Colin King wrote:
>>> From: Colin Ian King <colin.king@canonical.com>
>>>
>>> If pag cannot be allocated, the current error exit path will trip
>>> a null pointer deference error when calling xfs_buf_hash_destroy
>>> with a null pag.  Fix this by adding a new error exit lable and
>>> jumping to this, avoiding the hash destroy and unnecessary kmem_free
>>> on pag.
>>>
>>> Fixes CoverityScan CID#1397628 ("Dereference after null check")
>>>
>>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>>
>> Hm, I think this leaves the code with issues.
>>
>>> ---
>>>  fs/xfs/xfs_mount.c | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
>>> index 9b9540d..4e66cd19 100644
>>> --- a/fs/xfs/xfs_mount.c
>>> +++ b/fs/xfs/xfs_mount.c
>>> @@ -207,7 +207,7 @@ xfs_initialize_perag(
>>>  
>>>  		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
>>>  		if (!pag)
>>> -			goto out_unwind;
>>> +			goto out_unwind_pags;
>>
>> So let's say we got to index == 3 at the top of the loop, and
>> this fails.
>>
>> We succeeded in initializing 0, 1, and 2, but 3 failed.
>>
>> So we go to out_unwind_pags with index == 3...
>>
>>>  		pag->pag_agno = index;
>>>  		pag->pag_mount = mp;
>>>  		spin_lock_init(&pag->pag_ici_lock);
>>> @@ -242,6 +242,7 @@ xfs_initialize_perag(
>>>  out_unwind:
>>>  	xfs_buf_hash_destroy(pag);
>>>  	kmem_free(pag);
>>> +out_unwind_pags:
>>
>> ... where index == 3, and:
>>
>>>  	for (; index > first_initialised; index--) {
>>>  		pag = radix_tree_delete(&mp->m_perag_tree, index);
>>
>> this should fail, because it never got inserted, and...
>>
>>>  		xfs_buf_hash_destroy(pag);
>>
>> this still tries to destroy a NULL pag, no?
>>
>> There also seems to be an existing issue w/the code where ag 0 is
>> never torn down in the error case, because first_initialized doesn't
>> stay set to 0:
>>
>>                 if (!first_initialised)
>>                         first_initialised = index;
>>
>> And we don't even tear down ag 1, because:
>>
>>>  	for (; index > first_initialised; index--) {
>>>  		pag = radix_tree_delete(&mp->m_perag_tree, index);
>>
>> when the loop reaches the first initialized AG, it stops.
>>
>> So we seem to always leak at least 2 if we managed to get far enough
>> to initialize them.
> 
> Ugh, yeah, the the whole error exit from that function is fubar...
> Anyone want to clean this up?

I may step back on this if somebody else wants to fix this up properly.

> 
> --D
> 
>>
>> -Eric
>>
>>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html

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#1565926

On Fri, Jan 20, 2017 at 11:04:42PM +0000, Colin Ian King wrote:
> On 20/01/17 20:47, Darrick J. Wong wrote:
> > On Fri, Jan 20, 2017 at 01:26:12PM -0600, Eric Sandeen wrote:
> >> On 1/20/17 8:26 AM, Colin King wrote:
> >>> From: Colin Ian King <colin.king@canonical.com>
> >>>
> >>> If pag cannot be allocated, the current error exit path will trip
> >>> a null pointer deference error when calling xfs_buf_hash_destroy
> >>> with a null pag.  Fix this by adding a new error exit lable and
> >>> jumping to this, avoiding the hash destroy and unnecessary kmem_free
> >>> on pag.
> >>>
> >>> Fixes CoverityScan CID#1397628 ("Dereference after null check")
> >>>
> >>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> >>
> >> Hm, I think this leaves the code with issues.
> >>
> >>> ---
> >>>  fs/xfs/xfs_mount.c | 3 ++-
> >>>  1 file changed, 2 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> >>> index 9b9540d..4e66cd19 100644
> >>> --- a/fs/xfs/xfs_mount.c
> >>> +++ b/fs/xfs/xfs_mount.c
> >>> @@ -207,7 +207,7 @@ xfs_initialize_perag(
> >>>  
> >>>  		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
> >>>  		if (!pag)
> >>> -			goto out_unwind;
> >>> +			goto out_unwind_pags;
> >>
> >> So let's say we got to index == 3 at the top of the loop, and
> >> this fails.
> >>
> >> We succeeded in initializing 0, 1, and 2, but 3 failed.
> >>
> >> So we go to out_unwind_pags with index == 3...
> >>
> >>>  		pag->pag_agno = index;
> >>>  		pag->pag_mount = mp;
> >>>  		spin_lock_init(&pag->pag_ici_lock);
> >>> @@ -242,6 +242,7 @@ xfs_initialize_perag(
> >>>  out_unwind:
> >>>  	xfs_buf_hash_destroy(pag);
> >>>  	kmem_free(pag);
> >>> +out_unwind_pags:
> >>
> >> ... where index == 3, and:
> >>
> >>>  	for (; index > first_initialised; index--) {
> >>>  		pag = radix_tree_delete(&mp->m_perag_tree, index);
> >>
> >> this should fail, because it never got inserted, and...
> >>
> >>>  		xfs_buf_hash_destroy(pag);
> >>
> >> this still tries to destroy a NULL pag, no?
> >>
> >> There also seems to be an existing issue w/the code where ag 0 is
> >> never torn down in the error case, because first_initialized doesn't
> >> stay set to 0:
> >>
> >>                 if (!first_initialised)
> >>                         first_initialised = index;
> >>
> >> And we don't even tear down ag 1, because:
> >>
> >>>  	for (; index > first_initialised; index--) {
> >>>  		pag = radix_tree_delete(&mp->m_perag_tree, index);
> >>
> >> when the loop reaches the first initialized AG, it stops.
> >>
> >> So we seem to always leak at least 2 if we managed to get far enough
> >> to initialize them.
> > 
> > Ugh, yeah, the the whole error exit from that function is fubar...
> > Anyone want to clean this up?
> 
> I may step back on this if somebody else wants to fix this up properly.

I'll take it.
-Bill


> 
> > 
> > --D
> > 
> >>
> >> -Eric
> >>
> >>>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

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#1566051

On Tue, Jan 24, 2017 at 09:04:57AM -0600, Bill O'Donnell wrote:
> On Fri, Jan 20, 2017 at 11:04:42PM +0000, Colin Ian King wrote:
> > On 20/01/17 20:47, Darrick J. Wong wrote:
> > > On Fri, Jan 20, 2017 at 01:26:12PM -0600, Eric Sandeen wrote:
> > >> On 1/20/17 8:26 AM, Colin King wrote:
> > >>> From: Colin Ian King <colin.king@canonical.com>
> > >>>
> > >>> If pag cannot be allocated, the current error exit path will trip
> > >>> a null pointer deference error when calling xfs_buf_hash_destroy
> > >>> with a null pag.  Fix this by adding a new error exit lable and
> > >>> jumping to this, avoiding the hash destroy and unnecessary kmem_free
> > >>> on pag.
> > >>>
> > >>> Fixes CoverityScan CID#1397628 ("Dereference after null check")
> > >>>
> > >>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > >>
> > >> Hm, I think this leaves the code with issues.
> > >>
> > >>> ---
> > >>>  fs/xfs/xfs_mount.c | 3 ++-
> > >>>  1 file changed, 2 insertions(+), 1 deletion(-)
> > >>>
> > >>> diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
> > >>> index 9b9540d..4e66cd19 100644
> > >>> --- a/fs/xfs/xfs_mount.c
> > >>> +++ b/fs/xfs/xfs_mount.c
> > >>> @@ -207,7 +207,7 @@ xfs_initialize_perag(
> > >>>  
> > >>>  		pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
> > >>>  		if (!pag)
> > >>> -			goto out_unwind;
> > >>> +			goto out_unwind_pags;
> > >>
> > >> So let's say we got to index == 3 at the top of the loop, and
> > >> this fails.
> > >>
> > >> We succeeded in initializing 0, 1, and 2, but 3 failed.
> > >>
> > >> So we go to out_unwind_pags with index == 3...
> > >>
> > >>>  		pag->pag_agno = index;
> > >>>  		pag->pag_mount = mp;
> > >>>  		spin_lock_init(&pag->pag_ici_lock);
> > >>> @@ -242,6 +242,7 @@ xfs_initialize_perag(
> > >>>  out_unwind:
> > >>>  	xfs_buf_hash_destroy(pag);
> > >>>  	kmem_free(pag);
> > >>> +out_unwind_pags:
> > >>
> > >> ... where index == 3, and:
> > >>
> > >>>  	for (; index > first_initialised; index--) {
> > >>>  		pag = radix_tree_delete(&mp->m_perag_tree, index);
> > >>
> > >> this should fail, because it never got inserted, and...
> > >>
> > >>>  		xfs_buf_hash_destroy(pag);
> > >>
> > >> this still tries to destroy a NULL pag, no?
> > >>
> > >> There also seems to be an existing issue w/the code where ag 0 is
> > >> never torn down in the error case, because first_initialized doesn't
> > >> stay set to 0:
> > >>
> > >>                 if (!first_initialised)
> > >>                         first_initialised = index;
> > >>
> > >> And we don't even tear down ag 1, because:
> > >>
> > >>>  	for (; index > first_initialised; index--) {
> > >>>  		pag = radix_tree_delete(&mp->m_perag_tree, index);
> > >>
> > >> when the loop reaches the first initialized AG, it stops.
> > >>
> > >> So we seem to always leak at least 2 if we managed to get far enough
> > >> to initialize them.
> > > 
> > > Ugh, yeah, the the whole error exit from that function is fubar...
> > > Anyone want to clean this up?
> > 
> > I may step back on this if somebody else wants to fix this up properly.
> 
> I'll take it.

Acknowledged. :)

--D

> -Bill
> 
> 
> > 
> > > 
> > > --D
> > > 
> > >>
> > >> -Eric
> > >>
> > >>>
> > >> --
> > >> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > >> the body of a message to majordomo@vger.kernel.org
> > >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html

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