[PATCH] ext4: ext4_fill_super shouldn't return 0 on corruption

[PATCH] ext4: ext4_fill_super shouldn't return 0 on corruption

[Darrick J. Wong]

At the start of ext4_fill_super, ret is set to -EINVAL, and any failure path
out of that function returns this ret.  However, the generic_check_addressable
clause sets ret = 0 if it passes, which means that a subsequent failure (e.g.
a group checksum error) returns 0 even though the mount should fail.  This
causes vfs_kern_mount in turn to think that the mount succeeded (because
PTR_ERR(0) is false), leading to an oops.

A simple fix is to avoid using ret for the generic_check_addressable check,
which was last changed in commit 30ca22c70e3ef0a96ff84de69cd7e8561b416cb2.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---

 fs/ext4/super.c |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 40131b7..a44bc59 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3257,9 +3257,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	 * Test whether we have more sectors than will fit in sector_t,
 	 * and whether the max offset is addressable by the page cache.
 	 */
-	ret = generic_check_addressable(sb->s_blocksize_bits,
-					ext4_blocks_count(es));
-	if (ret) {
+	if (generic_check_addressable(sb->s_blocksize_bits,
+				      ext4_blocks_count(es))) {
 		ext4_msg(sb, KERN_ERR, "filesystem"
 			 " too large to mount safely on this system");
 		if (sizeof(sector_t) < 8)

Re: [PATCH] ext4: ext4_fill_super shouldn't return 0 on corruption

[Eric Sandeen]

On 11/15/10 3:48 PM, Darrick J. Wong wrote:
> At the start of ext4_fill_super, ret is set to -EINVAL, and any failure path
> out of that function returns this ret.  However, the generic_check_addressable
> clause sets ret = 0 if it passes, which means that a subsequent failure (e.g.
> a group checksum error) returns 0 even though the mount should fail.  This
> causes vfs_kern_mount in turn to think that the mount succeeded (because
> PTR_ERR(0) is false), leading to an oops.
> 
> A simple fix is to avoid using ret for the generic_check_addressable check,
> which was last changed in commit 30ca22c70e3ef0a96ff84de69cd7e8561b416cb2.
> 
> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>

looks right, but one comment below:

> ---
> 
>  fs/ext4/super.c |    5 ++---
>  1 files changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 40131b7..a44bc59 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3257,9 +3257,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  	 * Test whether we have more sectors than will fit in sector_t,
>  	 * and whether the max offset is addressable by the page cache.
>  	 */
> -	ret = generic_check_addressable(sb->s_blocksize_bits,
> -					ext4_blocks_count(es));
> -	if (ret) {
> +	if (generic_check_addressable(sb->s_blocksize_bits,
> +				      ext4_blocks_count(es))) {
>  		ext4_msg(sb, KERN_ERR, "filesystem"
>  			 " too large to mount safely on this system");
>  		if (sizeof(sector_t) < 8)

you probably want to set a "ret = -EFBIG" in here.

-Eric

> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
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[PATCH v2] ext4: ext4_fill_super shouldn't return 0 on corruption

[Darrick J. Wong]

At the start of ext4_fill_super, ret is set to -EINVAL, and any failure path
out of that function returns ret.  However, the generic_check_addressable
clause sets ret = 0 (if it passes), which means that a subsequent failure (e.g.
a group checksum error) returns 0 even though the mount should fail.  This
causes vfs_kern_mount in turn to think that the mount succeeded, leading to an
oops.

A simple fix is to avoid using ret for the generic_check_addressable check,
which was last changed in commit 30ca22c70e3ef0a96ff84de69cd7e8561b416cb2.

v2: Return -EFBIG in the error case, per Eric Sandeen's suggestion.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---

 fs/ext4/super.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 40131b7..120c034 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3257,13 +3257,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	 * Test whether we have more sectors than will fit in sector_t,
 	 * and whether the max offset is addressable by the page cache.
 	 */
-	ret = generic_check_addressable(sb->s_blocksize_bits,
-					ext4_blocks_count(es));
-	if (ret) {
+	if (generic_check_addressable(sb->s_blocksize_bits,
+				      ext4_blocks_count(es))) {
 		ext4_msg(sb, KERN_ERR, "filesystem"
 			 " too large to mount safely on this system");
 		if (sizeof(sector_t) < 8)
 			ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
+		ret = -EFBIG;
 		goto failed_mount;
 	}
 

Re: [PATCH v2] ext4: ext4_fill_super shouldn't return 0 on corruption

[Lukas Czerner]

On Mon, 15 Nov 2010, Darrick J. Wong wrote:

> At the start of ext4_fill_super, ret is set to -EINVAL, and any failure path
> out of that function returns ret.  However, the generic_check_addressable
> clause sets ret = 0 (if it passes), which means that a subsequent failure (e.g.
> a group checksum error) returns 0 even though the mount should fail.  This
> causes vfs_kern_mount in turn to think that the mount succeeded, leading to an
> oops.
> 
> A simple fix is to avoid using ret for the generic_check_addressable check,
> which was last changed in commit 30ca22c70e3ef0a96ff84de69cd7e8561b416cb2.
> 
> v2: Return -EFBIG in the error case, per Eric Sandeen's suggestion.
> 
> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
> ---
> 
>  fs/ext4/super.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 40131b7..120c034 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3257,13 +3257,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  	 * Test whether we have more sectors than will fit in sector_t,
>  	 * and whether the max offset is addressable by the page cache.
>  	 */
> -	ret = generic_check_addressable(sb->s_blocksize_bits,
> -					ext4_blocks_count(es));
> -	if (ret) {
> +	if (generic_check_addressable(sb->s_blocksize_bits,
> +				      ext4_blocks_count(es))) {
>  		ext4_msg(sb, KERN_ERR, "filesystem"
>  			 " too large to mount safely on this system");
>  		if (sizeof(sector_t) < 8)
>  			ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
> +		ret = -EFBIG;
>  		goto failed_mount;
>  	}
>  
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Hi,

the untested diff below seems like a more general solution to me,
since it allows to return the actual error from
generic_check_addressable().

Thanks.

-Lukas


diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 61182fe..3d89b72 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3268,13 +3268,14 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	 * Test whether we have more sectors than will fit in sector_t,
 	 * and whether the max offset is addressable by the page cache.
 	 */
-	ret = generic_check_addressable(sb->s_blocksize_bits,
+	err = generic_check_addressable(sb->s_blocksize_bits,
 					ext4_blocks_count(es));
-	if (ret) {
+	if (err) {
 		ext4_msg(sb, KERN_ERR, "filesystem"
 			 " too large to mount safely on this system");
 		if (sizeof(sector_t) < 8)
 			ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
+		ret = err;
 		goto failed_mount;
 	}
 

Re: [PATCH v2] ext4: ext4_fill_super shouldn't return 0 on corruption

[Eric Sandeen]

On 11/16/10 6:56 AM, Lukas Czerner wrote:
> On Mon, 15 Nov 2010, Darrick J. Wong wrote:
> 
>> At the start of ext4_fill_super, ret is set to -EINVAL, and any failure path
>> out of that function returns ret.  However, the generic_check_addressable
>> clause sets ret = 0 (if it passes), which means that a subsequent failure (e.g.
>> a group checksum error) returns 0 even though the mount should fail.  This
>> causes vfs_kern_mount in turn to think that the mount succeeded, leading to an
>> oops.
>>
>> A simple fix is to avoid using ret for the generic_check_addressable check,
>> which was last changed in commit 30ca22c70e3ef0a96ff84de69cd7e8561b416cb2.
>>
>> v2: Return -EFBIG in the error case, per Eric Sandeen's suggestion.
>>
>> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
>> ---
>>
>>  fs/ext4/super.c |    6 +++---
>>  1 files changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
>> index 40131b7..120c034 100644
>> --- a/fs/ext4/super.c
>> +++ b/fs/ext4/super.c
>> @@ -3257,13 +3257,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>>  	 * Test whether we have more sectors than will fit in sector_t,
>>  	 * and whether the max offset is addressable by the page cache.
>>  	 */
>> -	ret = generic_check_addressable(sb->s_blocksize_bits,
>> -					ext4_blocks_count(es));
>> -	if (ret) {
>> +	if (generic_check_addressable(sb->s_blocksize_bits,
>> +				      ext4_blocks_count(es))) {
>>  		ext4_msg(sb, KERN_ERR, "filesystem"
>>  			 " too large to mount safely on this system");
>>  		if (sizeof(sector_t) < 8)
>>  			ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
>> +		ret = -EFBIG;
>>  		goto failed_mount;
>>  	}
>>  
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
> 
> Hi,
> 
> the untested diff below seems like a more general solution to me,
> since it allows to return the actual error from
> generic_check_addressable().
> 
> Thanks.

good point, we can get -EINVAL or -EFBIG back, can't we.

Thanks,
-Eric

> -Lukas
> 
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 61182fe..3d89b72 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3268,13 +3268,14 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  	 * Test whether we have more sectors than will fit in sector_t,
>  	 * and whether the max offset is addressable by the page cache.
>  	 */
> -	ret = generic_check_addressable(sb->s_blocksize_bits,
> +	err = generic_check_addressable(sb->s_blocksize_bits,
>  					ext4_blocks_count(es));
> -	if (ret) {
> +	if (err) {
>  		ext4_msg(sb, KERN_ERR, "filesystem"
>  			 " too large to mount safely on this system");
>  		if (sizeof(sector_t) < 8)
>  			ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
> +		ret = err;
>  		goto failed_mount;
>  	}
>  

Re: [PATCH v2] ext4: ext4_fill_super shouldn't return 0 on corruption

[Darrick J. Wong]

On Tue, Nov 16, 2010 at 01:56:31PM +0100, Lukas Czerner wrote:
> On Mon, 15 Nov 2010, Darrick J. Wong wrote:
> 
> > At the start of ext4_fill_super, ret is set to -EINVAL, and any failure path
> > out of that function returns ret.  However, the generic_check_addressable
> > clause sets ret = 0 (if it passes), which means that a subsequent failure (e.g.
> > a group checksum error) returns 0 even though the mount should fail.  This
> > causes vfs_kern_mount in turn to think that the mount succeeded, leading to an
> > oops.
> > 
> > A simple fix is to avoid using ret for the generic_check_addressable check,
> > which was last changed in commit 30ca22c70e3ef0a96ff84de69cd7e8561b416cb2.
> > 
> > v2: Return -EFBIG in the error case, per Eric Sandeen's suggestion.
> > 
> > Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
> > ---
> > 
> >  fs/ext4/super.c |    6 +++---
> >  1 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> > index 40131b7..120c034 100644
> > --- a/fs/ext4/super.c
> > +++ b/fs/ext4/super.c
> > @@ -3257,13 +3257,13 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
> >  	 * Test whether we have more sectors than will fit in sector_t,
> >  	 * and whether the max offset is addressable by the page cache.
> >  	 */
> > -	ret = generic_check_addressable(sb->s_blocksize_bits,
> > -					ext4_blocks_count(es));
> > -	if (ret) {
> > +	if (generic_check_addressable(sb->s_blocksize_bits,
> > +				      ext4_blocks_count(es))) {
> >  		ext4_msg(sb, KERN_ERR, "filesystem"
> >  			 " too large to mount safely on this system");
> >  		if (sizeof(sector_t) < 8)
> >  			ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
> > +		ret = -EFBIG;
> >  		goto failed_mount;
> >  	}
> >  
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> 
> Hi,
> 
> the untested diff below seems like a more general solution to me,
> since it allows to return the actual error from
> generic_check_addressable().

It seems to work ok for me, so:

Acked-by: Darrick J. Wong <djwong@us.ibm.com>

I will make the same change to ext3.

--D
> 
> Thanks.
> 
> -Lukas
> 
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 61182fe..3d89b72 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3268,13 +3268,14 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
>  	 * Test whether we have more sectors than will fit in sector_t,
>  	 * and whether the max offset is addressable by the page cache.
>  	 */
> -	ret = generic_check_addressable(sb->s_blocksize_bits,
> +	err = generic_check_addressable(sb->s_blocksize_bits,
>  					ext4_blocks_count(es));
> -	if (ret) {
> +	if (err) {
>  		ext4_msg(sb, KERN_ERR, "filesystem"
>  			 " too large to mount safely on this system");
>  		if (sizeof(sector_t) < 8)
>  			ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
> +		ret = err;
>  		goto failed_mount;
>  	}
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

[PATCH] ext3: Return error code from generic_check_addressable

[Darrick J. Wong]

ext3: Return error code from generic_check_accessible

ext3_fill_super should return the error code that generic_check_accessible
returns when an error condition occurs.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
---

 fs/ext3/super.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 2fedaf8..960629b 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -1842,13 +1842,15 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
 		goto failed_mount;
 	}
 
-	if (generic_check_addressable(sb->s_blocksize_bits,
-				      le32_to_cpu(es->s_blocks_count))) {
+	err = generic_check_addressable(sb->s_blocksize_bits,
+					le32_to_cpu(es->s_blocks_count));
+	if (err) {
 		ext3_msg(sb, KERN_ERR,
 			"error: filesystem is too large to mount safely");
 		if (sizeof(sector_t) < 8)
 			ext3_msg(sb, KERN_ERR,
 				"error: CONFIG_LBDAF not enabled");
+		ret = err;
 		goto failed_mount;
 	}
 

Re: [PATCH] ext3: Return error code from generic_check_addressable

[Lukas Czerner]

On Tue, 16 Nov 2010, Darrick J. Wong wrote:

> ext3: Return error code from generic_check_accessible
> 
> ext3_fill_super should return the error code that generic_check_accessible
> returns when an error condition occurs.
> 
> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
> ---
> 
>  fs/ext3/super.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> index 2fedaf8..960629b 100644
> --- a/fs/ext3/super.c
> +++ b/fs/ext3/super.c
> @@ -1842,13 +1842,15 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
>  		goto failed_mount;
>  	}
>  
> -	if (generic_check_addressable(sb->s_blocksize_bits,
> -				      le32_to_cpu(es->s_blocks_count))) {
> +	err = generic_check_addressable(sb->s_blocksize_bits,
> +					le32_to_cpu(es->s_blocks_count));
> +	if (err) {
>  		ext3_msg(sb, KERN_ERR,
>  			"error: filesystem is too large to mount safely");
>  		if (sizeof(sector_t) < 8)
>  			ext3_msg(sb, KERN_ERR,
>  				"error: CONFIG_LBDAF not enabled");
> +		ret = err;
>  		goto failed_mount;
>  	}
>  
> 

Add Jan Kara to cc list.

-Lukas

Re: [PATCH v2] ext4: ext4_fill_super shouldn't return 0 on corruption

[Ted Ts'o]

On Tue, Nov 16, 2010 at 02:55:38PM -0800, Darrick J. Wong wrote:
> > the untested diff below seems like a more general solution to me,
> > since it allows to return the actual error from
> > generic_check_addressable().
> 
> It seems to work ok for me, so:
> 
> Acked-by: Darrick J. Wong <djwong@us.ibm.com>
> 
> I will make the same change to ext3.

OK, this is what I've added to the ext4 patch queue

---
ext4: ext4_fill_super shouldn't return 0 on corruption

From: "Darrick J. Wong" <djwong@us.ibm.com>

At the start of ext4_fill_super, ret is set to -EINVAL, and any
failure path out of that function returns ret.  However, the
generic_check_addressable clause sets ret = 0 (if it passes), which
means that a subsequent failure (e.g.  a group checksum error) returns
0 even though the mount should fail.  This causes vfs_kern_mount in
turn to think that the mount succeeded, leading to an oops.

A simple fix is to avoid using ret for the generic_check_addressable
check, which was last changed in commit 30ca22c70e3.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 61182fe..3d89b72 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3268,13 +3268,14 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	 * Test whether we have more sectors than will fit in sector_t,
 	 * and whether the max offset is addressable by the page cache.
 	 */
-	ret = generic_check_addressable(sb->s_blocksize_bits,
+	err = generic_check_addressable(sb->s_blocksize_bits,
 					ext4_blocks_count(es));
-	if (ret) {
+	if (err) {
 		ext4_msg(sb, KERN_ERR, "filesystem"
 			 " too large to mount safely on this system");
 		if (sizeof(sector_t) < 8)
 			ext4_msg(sb, KERN_WARNING, "CONFIG_LBDAF not enabled");
+		ret = err;
 		goto failed_mount;
 	}
 

Re: [PATCH] ext3: Return error code from generic_check_addressable

[Jan Kara]

On Thu 18-11-10 09:52:51, Lukas Czerner wrote:
> On Tue, 16 Nov 2010, Darrick J. Wong wrote:
> 
> > ext3: Return error code from generic_check_accessible
> > 
> > ext3_fill_super should return the error code that generic_check_accessible
> > returns when an error condition occurs.
> > 
> > Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
> > ---
> > 
> >  fs/ext3/super.c |    6 ++++--
> >  1 files changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/ext3/super.c b/fs/ext3/super.c
> > index 2fedaf8..960629b 100644
> > --- a/fs/ext3/super.c
> > +++ b/fs/ext3/super.c
> > @@ -1842,13 +1842,15 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
> >  		goto failed_mount;
> >  	}
> >  
> > -	if (generic_check_addressable(sb->s_blocksize_bits,
> > -				      le32_to_cpu(es->s_blocks_count))) {
> > +	err = generic_check_addressable(sb->s_blocksize_bits,
> > +					le32_to_cpu(es->s_blocks_count));
> > +	if (err) {
> >  		ext3_msg(sb, KERN_ERR,
> >  			"error: filesystem is too large to mount safely");
> >  		if (sizeof(sector_t) < 8)
> >  			ext3_msg(sb, KERN_ERR,
> >  				"error: CONFIG_LBDAF not enabled");
> > +		ret = err;
> >  		goto failed_mount;
> >  	}
> >  
> > 
> 
> Add Jan Kara to cc list.
  Thanks for forwarding. Merged.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR