[PATCH 4.4 53/53] xfs: only return -errno or success from attr ->put_listent

Greg Kroah-Hartman
2017-06-05T16:22:31Z

From: Eric Sandeen <sandeen@sandeen.net>

commit 2a6fba6d2311151598abaa1e7c9abd5f8d024a43 upstream.

Today, the put_listent formatters return either 1 or 0; if
they return 1, some callers treat this as an error and return
it up the stack, despite "1" not being a valid (negative)
error code.

The intent seems to be that if the input buffer is full,
we set seen_enough or set count = -1, and return 1;
but some callers check the return before checking the
seen_enough or count fields of the context.

Fix this by only returning non-zero for actual errors
encountered, and rely on the caller to first check the
return value, then check the values in the context to
decide what to do.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/xfs_attr.h | 1 +
fs/xfs/xfs_attr_list.c | 8 +++-----
fs/xfs/xfs_xattr.c | 15 ++++++++++-----
3 files changed, 14 insertions(+), 10 deletions(-)

--- a/fs/xfs/xfs_attr.h
+++ b/fs/xfs/xfs_attr.h
@@ -112,6 +112,7 @@ typedef struct attrlist_cursor_kern {
*========================================================================*/

+/* Return 0 on success, or -errno; other state communicated via *context */
typedef int (*put_listent_func_t)(struct xfs_attr_list_context *, int,
unsigned char *, int, int, unsigned char *);

--- a/fs/xfs/xfs_attr_list.c
+++ b/fs/xfs/xfs_attr_list.c
@@ -108,16 +108,14 @@ xfs_attr_shortform_list(xfs_attr_list_co
(int)sfe->namelen,
(int)sfe->valuelen,
&sfe->nameval[sfe->namelen]);
-
+ if (error)
+ return error;
/*
* Either search callback finished early or
* didn't fit it all in the buffer after all.
*/
if (context->seen_enough)
break;
-
- if (error)
- return error;
sfe = XFS_ATTR_SF_NEXTENTRY(sfe);
}
trace_xfs_attr_list_sf_all(context);
@@ -581,7 +579,7 @@ xfs_attr_put_listent(
trace_xfs_attr_list_full(context);
alist->al_more = 1;
context->seen_enough = 1;
- return 1;
+ return 0;
}

aep = (attrlist_ent_t *)&context->alist[context->firstu];
--- a/fs/xfs/xfs_xattr.c
+++ b/fs/xfs/xfs_xattr.c
@@ -180,7 +180,7 @@ xfs_xattr_put_listent(
arraytop = context->count + prefix_len + namelen + 1;
if (arraytop > context->firstu) {
context->count = -1; /* insufficient space */
- return 1;
+ return 0;
}
offset = (char *)context->alist + context->count;
strncpy(offset, xfs_xattr_prefix(flags), prefix_len);
@@ -222,12 +222,15 @@ list_one_attr(const char *name, const si
}

ssize_t
-xfs_vn_listxattr(struct dentry *dentry, char *data, size_t size)
+xfs_vn_listxattr(
+ struct dentry *dentry,
+ char *data,
+ size_t size)
{
struct xfs_attr_list_context context;
struct attrlist_cursor_kern cursor = { 0 };
- struct inode *inode = d_inode(dentry);
- int error;
+ struct inode *inode = d_inode(dentry);
+ int error;

/*
* First read the regular on-disk attributes.
@@ -245,7 +248,9 @@ xfs_vn_listxattr(struct dentry *dentry,
else
context.put_listent = xfs_xattr_put_listent_sizes;

- xfs_attr_list_int(&context);
+ error = xfs_attr_list_int(&context);
+ if (error)
+ return error;
if (context.count < 0)
return -ERANGE;