gfs2: Don't leave s_fs_info pointing to freed memory in init_sbd

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>

diff --git a/fs/gfs2/ops_fstype.c b/fs/gfs2/ops_fstype.c
index 28d6c65..057be88 100644 (file)
--- a/fs/gfs2/ops_fstype.c
+++ b/fs/gfs2/ops_fstype.c
@@ -72,13 +72,13 @@ static struct gfs2_sbd *init_sbd(struct super_block *sb)
        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);