[PATCH 5.5 189/367] NFS: Fix memory leaks and corruption in readdir

Greg Kroah-Hartman
2020-02-10T12:49:48Z

From: Trond Myklebust <trondmy@gmail.com>

commit 4b310319c6a8ce708f1033d57145e2aa027a883c upstream.

nfs_readdir_xdr_to_array() must not exit without having initialised
the array, so that the page cache deletion routines can safely
call nfs_readdir_clear_array().
Furthermore, we should ensure that if we exit nfs_readdir_filler()
with an error, we free up any page contents to prevent a leak
if we try to fill the page again.

Fixes: 11de3b11e08c ("NFS: Fix a memory leak in nfs_readdir")
Cc: stable@vger.kernel.org # v2.6.37+
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/nfs/dir.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -162,6 +162,17 @@ typedef struct {
bool eof;
} nfs_readdir_descriptor_t;

+static
+void nfs_readdir_init_array(struct page *page)
+{
+ struct nfs_cache_array *array;
+
+ array = kmap_atomic(page);
+ memset(array, 0, sizeof(struct nfs_cache_array));
+ array->eof_index = -1;
+ kunmap_atomic(array);
+}
+
/*
* we are freeing strings created by nfs_add_to_readdir_array()
*/
@@ -174,6 +185,7 @@ void nfs_readdir_clear_array(struct page
array = kmap_atomic(page);
for (i = 0; i < array->size; i++)
kfree(array->array[i].string.name);
+ array->size = 0;
kunmap_atomic(array);
}

@@ -610,6 +622,8 @@ int nfs_readdir_xdr_to_array(nfs_readdir
int status = -ENOMEM;
unsigned int array_size = ARRAY_SIZE(pages);

+ nfs_readdir_init_array(page);
+
entry.prev_cookie = 0;
entry.cookie = desc->last_cookie;
entry.eof = 0;
@@ -626,8 +640,6 @@ int nfs_readdir_xdr_to_array(nfs_readdir
}

array = kmap(page);
- memset(array, 0, sizeof(struct nfs_cache_array));
- array->eof_index = -1;

status = nfs_readdir_alloc_pages(pages, array_size);
if (status < 0)
@@ -682,6 +694,7 @@ int nfs_readdir_filler(void *data, struc
unlock_page(page);
return 0;
error:
+ nfs_readdir_clear_array(page);
unlock_page(page);
return ret;
}