[PATCH 5.12 021/296] NFSv4: Fix a NULL pointer dereference in pnfs_mark_matching_lsegs_return()

Greg Kroah-Hartman
2021-05-31T16:04:34Z

From: Anna Schumaker <Anna.Schumaker@Netapp.com>

commit a421d218603ffa822a0b8045055c03eae394a7eb upstream.

Commit de144ff4234f changes _pnfs_return_layout() to call
pnfs_mark_matching_lsegs_return() passing NULL as the struct
pnfs_layout_range argument. Unfortunately,
pnfs_mark_matching_lsegs_return() doesn't check if we have a value here
before dereferencing it, causing an oops.

I'm able to hit this crash consistently when running connectathon basic
tests on NFS v4.1/v4.2 against Ontap.

Fixes: de144ff4234f ("NFSv4: Don't discard segments marked for return in _pnfs_return_layout()")
Cc: stable@vger.kernel.org
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfs/pnfs.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)

--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1317,6 +1317,11 @@ _pnfs_return_layout(struct inode *ino)
{
struct pnfs_layout_hdr *lo = NULL;
struct nfs_inode *nfsi = NFS_I(ino);
+ struct pnfs_layout_range range = {
+ .iomode = IOMODE_ANY,
+ .offset = 0,
+ .length = NFS4_MAX_UINT64,
+ };
LIST_HEAD(tmp_list);
const struct cred *cred;
nfs4_stateid stateid;
@@ -1344,16 +1349,10 @@ _pnfs_return_layout(struct inode *ino)
}
valid_layout = pnfs_layout_is_valid(lo);
pnfs_clear_layoutcommit(ino, &tmp_list);
- pnfs_mark_matching_lsegs_return(lo, &tmp_list, NULL, 0);
+ pnfs_mark_matching_lsegs_return(lo, &tmp_list, &range, 0);

- if (NFS_SERVER(ino)->pnfs_curr_ld->return_range) {
- struct pnfs_layout_range range = {
- .iomode = IOMODE_ANY,
- .offset = 0,
- .length = NFS4_MAX_UINT64,
- };
+ if (NFS_SERVER(ino)->pnfs_curr_ld->return_range)
NFS_SERVER(ino)->pnfs_curr_ld->return_range(lo, &range);
- }

/* Don't send a LAYOUTRETURN if list was initially empty */
if (!test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags) ||