[PATCH 4.4 08/86] gfs2: Dont leave s_fs_info pointing to freed memory in init_sbd

Greg Kroah-Hartman
2018-11-29T14:18:12Z

From: Andrew Price <anprice@redhat.com>

commit 4c62bd9cea7bcf10292f7e4c57a2bca332942697 upstream.

When alloc_percpu() fails, sdp gets freed but sb->s_fs_info still points
to the same address. Move the assignment after that error check so that
s_fs_info can only point to a valid sdp or NULL, which is checked for
later in the error path, in gfs2_kill_super().

Reported-by: syzbot+dcb8b3587445007f5808@syzkaller.appspotmail.com
Signed-off-by: Andrew Price <anprice@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/gfs2/ops_fstype.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -71,13 +71,13 @@ static struct gfs2_sbd *init_sbd(struct
if (!sdp)
return NULL;

- sb->s_fs_info = sdp;
sdp->sd_vfs = sb;
sdp->sd_lkstats = alloc_percpu(struct gfs2_pcpu_lkstats);
if (!sdp->sd_lkstats) {
kfree(sdp);
return NULL;
}
+ sb->s_fs_info = sdp;

set_bit(SDF_NOJOURNALID, &sdp->sd_flags);
gfs2_tune_init(&sdp->sd_tune);