[PATCH AUTOSEL 4.14 127/371] NFSv4/flexfiles: Fix invalid deref in FF_LAYOUT_DEVID_NODE()

Sasha Levin
2020-01-16T18:29:27Z

From: Trond Myklebust <trond.myklebust@hammerspace.com>

[ Upstream commit 108bb4afd351d65826648a47f11fa3104e250d9b ]

If the attempt to instantiate the mirror's layout DS pointer failed,
then that pointer may hold a value of type ERR_PTR(), so we need
to check that before we dereference it.

Fixes: 65990d1afbd2d ("pNFS/flexfiles: Fix a deadlock on LAYOUTGET")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/nfs/flexfilelayout/flexfilelayout.h | 32 +++++++++++++++-----------
1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.h b/fs/nfs/flexfilelayout/flexfilelayout.h
index d6515f1584f3..d78ec99b6c4c 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.h
+++ b/fs/nfs/flexfilelayout/flexfilelayout.h
@@ -131,16 +131,6 @@ FF_LAYOUT_LSEG(struct pnfs_layout_segment *lseg)
generic_hdr);
}

-static inline struct nfs4_deviceid_node *
-FF_LAYOUT_DEVID_NODE(struct pnfs_layout_segment *lseg, u32 idx)
-{
- if (idx >= FF_LAYOUT_LSEG(lseg)->mirror_array_cnt ||
- FF_LAYOUT_LSEG(lseg)->mirror_array[idx] == NULL ||
- FF_LAYOUT_LSEG(lseg)->mirror_array[idx]->mirror_ds == NULL)
- return NULL;
- return &FF_LAYOUT_LSEG(lseg)->mirror_array[idx]->mirror_ds->id_node;
-}
-
static inline struct nfs4_ff_layout_ds *
FF_LAYOUT_MIRROR_DS(struct nfs4_deviceid_node *node)
{
@@ -150,9 +140,25 @@ FF_LAYOUT_MIRROR_DS(struct nfs4_deviceid_node *node)
static inline struct nfs4_ff_layout_mirror *
FF_LAYOUT_COMP(struct pnfs_layout_segment *lseg, u32 idx)
{
- if (idx >= FF_LAYOUT_LSEG(lseg)->mirror_array_cnt)
- return NULL;
- return FF_LAYOUT_LSEG(lseg)->mirror_array[idx];
+ struct nfs4_ff_layout_segment *fls = FF_LAYOUT_LSEG(lseg);
+
+ if (idx < fls->mirror_array_cnt)
+ return fls->mirror_array[idx];
+ return NULL;
+}
+
+static inline struct nfs4_deviceid_node *
+FF_LAYOUT_DEVID_NODE(struct pnfs_layout_segment *lseg, u32 idx)
+{
+ struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, idx);
+
+ if (mirror != NULL) {
+ struct nfs4_ff_layout_ds *mirror_ds = mirror->mirror_ds;
+
+ if (!IS_ERR_OR_NULL(mirror_ds))
+ return &mirror_ds->id_node;
+ }
+ return NULL;
}

static inline u32
--
2.20.1