[PATCH] xfs_repair: properly detect reserved attribute names

[PATCH] xfs_repair: properly detect reserved attribute names

[Eric Sandeen]

This function in xfs_repair tries to make sure that if an attr
name reserved for acls exists in the root namespace, then its
value is a valid acl.

However, because it only compares up to the length of the
reserved name, superstrings may match and cause false positive
xfs_repair errors.

Ensure that both the length and the content match before
flagging it as an error.

Spotted-by: Zach Brown <zab@zabbo.net>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

diff --git a/repair/attr_repair.c b/repair/attr_repair.c
index 27442c4..89a5bbf 100644
--- a/repair/attr_repair.c
+++ b/repair/attr_repair.c
@@ -747,9 +747,10 @@ valuecheck(
 	void *valuep;
 	int clearit = 0;
 
-	if ((strncmp(namevalue, SGI_ACL_FILE, SGI_ACL_FILE_SIZE) == 0) ||
-			(strncmp(namevalue, SGI_ACL_DEFAULT,
-				SGI_ACL_DEFAULT_SIZE) == 0)) {
+	if ((namelen == SGI_ACL_FILE_SIZE &&
+	     strncmp(namevalue, SGI_ACL_FILE, SGI_ACL_FILE_SIZE) == 0) ||
+	    (namelen == SGI_ACL_DEFAULT_SIZE &&
+	     strncmp(namevalue, SGI_ACL_DEFAULT, SGI_ACL_DEFAULT_SIZE) == 0)) {
 		if (value == NULL) {
 			valuep = malloc(valuelen);
 			if (!valuep)

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Re: [PATCH] xfs_repair: properly detect reserved attribute names

[Brian Foster]

On Wed, May 13, 2015 at 10:29:42PM -0500, Eric Sandeen wrote:
> This function in xfs_repair tries to make sure that if an attr
> name reserved for acls exists in the root namespace, then its
> value is a valid acl.
> 
> However, because it only compares up to the length of the
> reserved name, superstrings may match and cause false positive
> xfs_repair errors.
> 
> Ensure that both the length and the content match before
> flagging it as an error.
> 
> Spotted-by: Zach Brown <zab@zabbo.net>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---

Looks good:

Reviewed-by: Brian Foster <bfoster@redhat.com>

So it looks like master doesn't have the sizeof(unsigned char *)
problem and the 4.1 update branch does, so we want to make sure that
kernel fix makes it into the latter...

> 
> diff --git a/repair/attr_repair.c b/repair/attr_repair.c
> index 27442c4..89a5bbf 100644
> --- a/repair/attr_repair.c
> +++ b/repair/attr_repair.c
> @@ -747,9 +747,10 @@ valuecheck(
>  	void *valuep;
>  	int clearit = 0;
>  
> -	if ((strncmp(namevalue, SGI_ACL_FILE, SGI_ACL_FILE_SIZE) == 0) ||
> -			(strncmp(namevalue, SGI_ACL_DEFAULT,
> -				SGI_ACL_DEFAULT_SIZE) == 0)) {
> +	if ((namelen == SGI_ACL_FILE_SIZE &&
> +	     strncmp(namevalue, SGI_ACL_FILE, SGI_ACL_FILE_SIZE) == 0) ||
> +	    (namelen == SGI_ACL_DEFAULT_SIZE &&
> +	     strncmp(namevalue, SGI_ACL_DEFAULT, SGI_ACL_DEFAULT_SIZE) == 0)) {
>  		if (value == NULL) {
>  			valuep = malloc(valuelen);
>  			if (!valuep)
> 
> _______________________________________________
> xfs mailing list
> xfs@oss.sgi.com
> http://oss.sgi.com/mailman/listinfo/xfs

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Re: [PATCH] xfs_repair: properly detect reserved attribute names

[Eric Sandeen]

On 5/14/15 9:22 AM, Brian Foster wrote:
> On Wed, May 13, 2015 at 10:29:42PM -0500, Eric Sandeen wrote:
>> This function in xfs_repair tries to make sure that if an attr
>> name reserved for acls exists in the root namespace, then its
>> value is a valid acl.
>>
>> However, because it only compares up to the length of the
>> reserved name, superstrings may match and cause false positive
>> xfs_repair errors.
>>
>> Ensure that both the length and the content match before
>> flagging it as an error.
>>
>> Spotted-by: Zach Brown <zab@zabbo.net>
>> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
>> ---
> 
> Looks good:
> 
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> 
> So it looks like master doesn't have the sizeof(unsigned char *)
> problem and the 4.1 update branch does, so we want to make sure that
> kernel fix makes it into the latter...

Yep.  This fix is needed independently of that, though.

Thanks!
-Eric

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