Commit 35264909 authored by Andreas Gruenbacher's avatar Andreas Gruenbacher
Browse files

gfs2: Fix NULL pointer dereference in gfs2_log_flush 



In gfs2_jindex_free(), set sdp->sd_jdesc to NULL under the log flush
lock to provide exclusion against gfs2_log_flush().

In gfs2_log_flush(), check if sdp->sd_jdesc is non-NULL before
dereferencing it.  Otherwise, we could run into a NULL pointer
dereference when outstanding glock work races with an unmount
(glock_work_func -> run_queue -> do_xmote -> inode_go_sync ->
gfs2_log_flush).

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
parent b0118933

fs/gfs2/log.c

+2 −1
Original line number Diff line number Diff line
@@ -1108,6 +1108,7 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl, u32 flags) 
	lops_before_commit(sdp, tr);

	if (gfs2_withdrawing_or_withdrawn(sdp))

		goto out_withdraw;

	if (sdp->sd_jdesc)

		gfs2_log_submit_bio(&sdp->sd_jdesc->jd_log_bio, REQ_OP_WRITE);

	if (gfs2_withdrawing_or_withdrawn(sdp))

		goto out_withdraw;

fs/gfs2/super.c

+4 −0
Original line number Diff line number Diff line
@@ -67,9 +67,13 @@ void gfs2_jindex_free(struct gfs2_sbd *sdp) 
	sdp->sd_journals = 0;

	spin_unlock(&sdp->sd_jindex_spin);



	down_write(&sdp->sd_log_flush_lock);

	sdp->sd_jdesc = NULL;

	up_write(&sdp->sd_log_flush_lock);



	while (!list_empty(&list)) {

		jd = list_first_entry(&list, struct gfs2_jdesc, jd_list);

		BUG_ON(jd->jd_log_bio);

		gfs2_free_journal_extents(jd);

		list_del(&jd->jd_list);

		iput(jd->jd_inode);