[PATCH] nfs: Fix listxattr regression

[PATCH] nfs: Fix listxattr regression

[Andreas Gruenbacher]

Al,

the xattr cleanup patches which are meanwhile in your for-next branch broke
listxattr on nfs.  Could you please add this fix?

Thanks,
Andreas

--

In removing the list operation of nfs4_xattr_nfs4_label_handler, commit
d77ae742 has introduced a NULL pointer dereference in generic_listxattr.
Fix by checking for NULL list operations.  In addition, skip prefix (as
opposed to full-name) xattr handlers there: listing a prefix is not
meaningful.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/xattr.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/xattr.c b/fs/xattr.c
index bfd4a85..477bda2 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -723,15 +723,18 @@ generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 
 	if (!buffer) {
 		for_each_xattr_handler(handlers, handler) {
-			if (handler->list(dentry))
-				size += strlen(handler->name) + 1;
+			if (!handler->name ||
+			    (handler->list && !handler->list(dentry)))
+				continue;
+			size += strlen(handler->name) + 1;
 		}
 	} else {
 		char *buf = buffer;
 		size_t len;
 
 		for_each_xattr_handler(handlers, handler) {
-			if (!handler->list(dentry))
+			if (!handler->name ||
+			    (handler->list && !handler->list(dentry)))
 				continue;
 			len = strlen(handler->name);
 			if (len + 1 > buffer_size)
-- 
2.5.0

Re: [PATCH] nfs: Fix listxattr regression

[Al Viro]

On Fri, Dec 11, 2015 at 01:15:46PM +0100, Andreas Gruenbacher wrote:
> Al,
> 
> the xattr cleanup patches which are meanwhile in your for-next branch broke
> listxattr on nfs.  Could you please add this fix?

Umm...  Would you be OK with folding that into commit in question?  I'd
rather not introduce a bisect hazard in the first place...

Re: [PATCH] nfs: Fix listxattr regression

[Andreas Gruenbacher]

On Fri, Dec 11, 2015 at 1:55 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Fri, Dec 11, 2015 at 01:15:46PM +0100, Andreas Gruenbacher wrote:
>> Al,
>>
>> the xattr cleanup patches which are meanwhile in your for-next branch broke
>> listxattr on nfs.  Could you please add this fix?
>
> Umm...  Would you be OK with folding that into commit in question?  I'd
> rather not introduce a bisect hazard in the first place...

Yes sure, if you are okay with rebasing.

I assume that there is no point in reposting the xattr cleanups with
this fix included; if you would prefer a repost, let me know.

Thanks,
Andreas

[PATCH] nfs: Fix listxattr regression (2)

[Andreas Gruenbacher]

Al,

here is another fix for the same botched nfs commit.  Could you please
also merge / fold that?  Sorry for the mess.

Thanks,
Andreas

--

Fix another regression introduced in d77ae742: listxattr ended up always
failing with -ERANGE on NFSv4.2 mounts with security label support.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/nfs/nfs4proc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index e9db118..c57d133 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6296,8 +6296,8 @@ nfs4_listxattr_nfs4_label(struct inode *inode, char *list, size_t list_len)
 	int len = 0;
 
 	if (nfs_server_capable(inode, NFS_CAP_SECURITY_LABEL)) {
-		len = security_inode_listsecurity(inode, list, len);
-		if (len > list_len)
+		len = security_inode_listsecurity(inode, list, list_len);
+		if (list_len && len > list_len)
 			return -ERANGE;
 	}
 	return len;
-- 
2.5.0

Re: [PATCH] nfs: Fix listxattr regression (2)

[Andreas Gruenbacher]

On Fri, Dec 11, 2015 at 4:14 PM, Andreas Gruenbacher <agruenba@redhat.com> wrote:
> Al,
>
> here is another fix for the same botched nfs commit.  Could you please
> also merge / fold that?  Sorry for the mess.

I've pushed a branch with those two fixes here:

  git://git.kernel.org/pub/scm/linux/kernel/git/agruen/linux xattr-wip2

This is your work.xattr branch with the fixes folded in and with your
Signed-off-by tags removed from the two commits that have been modified:

  nfs: Move call to security_inode_listsecurity into nfs_listxattr
  xattr handlers: Simplify list operation

Diff between work.xattr and xattr-wip2 below.

Thanks,
Andreas

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index e9db118..c57d133 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -6296,8 +6296,8 @@ nfs4_listxattr_nfs4_label(struct inode *inode, char *list, size_t list_len)
 	int len = 0;
 
 	if (nfs_server_capable(inode, NFS_CAP_SECURITY_LABEL)) {
-		len = security_inode_listsecurity(inode, list, len);
-		if (len > list_len)
+		len = security_inode_listsecurity(inode, list, list_len);
+		if (list_len && len > list_len)
 			return -ERANGE;
 	}
 	return len;
diff --git a/fs/xattr.c b/fs/xattr.c
index bfd4a85..d7f5037 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -723,21 +723,23 @@ generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 
 	if (!buffer) {
 		for_each_xattr_handler(handlers, handler) {
-			if (handler->list(dentry))
-				size += strlen(handler->name) + 1;
+			if (!handler->name ||
+			    (handler->list && !handler->list(dentry)))
+				continue;
+			size += strlen(handler->name) + 1;
 		}
 	} else {
 		char *buf = buffer;
 		size_t len;
 
 		for_each_xattr_handler(handlers, handler) {
-			if (!handler->list(dentry))
+			if (!handler->name ||
+			    (handler->list && !handler->list(dentry)))
 				continue;
 			len = strlen(handler->name);
 			if (len + 1 > buffer_size)
 				return -ERANGE;
-			memcpy(buf, handler->name, len);
-			buf[len] = 0;
+			memcpy(buf, handler->name, len + 1);
 			buf += len + 1;
 			buffer_size -= len + 1;
 		}