From: Jeff Layton <jlayton@kernel.org>
Date: Wed, 8 Apr 2020 08:41:38 -0400
Subject: ceph: fix potential bad pointer deref in async dirops cb's
Git-commit: 2a575f138d003fff0f4930b5cfae4a1c46343b8f
Patch-mainline: v5.7-rc2
References: bsc#1171390

The new async dirops callback routines can pass ERR_PTR values to
ceph_mdsc_free_path, which could cause an oops. Make ceph_mdsc_free_path
ignore ERR_PTR values. Also, ensure that the pr_warn messages look sane
even if ceph_mdsc_build_path fails.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
 fs/ceph/dir.c        | 4 ++--
 fs/ceph/file.c       | 4 ++--
 fs/ceph/mds_client.h | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
index d594c2627430..4c4202c93b71 100644
--- a/fs/ceph/dir.c
+++ b/fs/ceph/dir.c
@@ -1051,8 +1051,8 @@ static void ceph_async_unlink_cb(struct ceph_mds_client *mdsc,
 
 	/* If op failed, mark everyone involved for errors */
 	if (result) {
-		int pathlen;
-		u64 base;
+		int pathlen = 0;
+		u64 base = 0;
 		char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
 						  &base, 0);
 
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 4a5ccbb7e808..afdfca965a7f 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -527,8 +527,8 @@ static void ceph_async_create_cb(struct ceph_mds_client *mdsc,
 
 	if (result) {
 		struct dentry *dentry = req->r_dentry;
-		int pathlen;
-		u64 base;
+		int pathlen = 0;
+		u64 base = 0;
 		char *path = ceph_mdsc_build_path(req->r_dentry, &pathlen,
 						  &base, 0);
 
diff --git a/fs/ceph/mds_client.h b/fs/ceph/mds_client.h
index 4e5be79bf080..903d9edfd4bf 100644
--- a/fs/ceph/mds_client.h
+++ b/fs/ceph/mds_client.h
@@ -521,7 +521,7 @@ extern void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc);
 
 static inline void ceph_mdsc_free_path(char *path, int len)
 {
-	if (path)
+	if (!IS_ERR_OR_NULL(path))
 		__putname(path - (PATH_MAX - 1 - len));
 }