[PATCH 4.9 129/153] NFSv4: fix getacl ERANGE for some ACL buffer sizes

Greg Kroah-Hartman
2017-03-10T09:24:49Z

From: Weston Andros Adamson <dros@primarydata.com>

commit ed92d8c137b7794c2c2aa14479298b9885967607 upstream.

We're not taking into account that the space needed for the (variable
length) attr bitmap, with the result that we'd sometimes get a spurious
ERANGE when the ACL data got close to the end of a page.

Just add in an extra page to make sure.

Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/nfs/nfs4proc.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -4990,7 +4990,7 @@ out:
*/
static ssize_t __nfs4_get_acl_uncached(struct inode *inode, void *buf, size_t buflen)
{
- struct page *pages[NFS4ACL_MAXPAGES] = {NULL, };
+ struct page *pages[NFS4ACL_MAXPAGES + 1] = {NULL, };
struct nfs_getaclargs args = {
.fh = NFS_FH(inode),
.acl_pages = pages,
@@ -5004,13 +5004,9 @@ static ssize_t __nfs4_get_acl_uncached(s
.rpc_argp = &args,
.rpc_resp = &res,
};
- unsigned int npages = DIV_ROUND_UP(buflen, PAGE_SIZE);
+ unsigned int npages = DIV_ROUND_UP(buflen, PAGE_SIZE) + 1;
int ret = -ENOMEM, i;

- /* As long as we're doing a round trip to the server anyway,
- * let's be prepared for a page of acl data. */
- if (npages == 0)
- npages = 1;
if (npages > ARRAY_SIZE(pages))
return -ERANGE;