[Cluster-devel] [GFS2 PATCH] gfs2: fix use-after-free in trans_drain
Bob Peterson
rpeterso at redhat.com
Wed Mar 3 16:11:59 UTC 2021
This patch adds code to function trans_drain to remove drained
bd elements from the ail lists, if queued, before freeing the bd.
If we don't remove the bd from the ail, function ail_drain will
try to reference the bd after it has been freed by trans_drain.
Thanks to Andy Price for his analysis of the problem.
Reported-by: Andy Price <anprice at redhat.com>
Signed-off-by: Bob Peterson <rpeterso at redhat.com>
---
fs/gfs2/log.c | 4 ++++
fs/gfs2/trans.c | 2 ++
2 files changed, 6 insertions(+)
diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 16937ebb2a3e..760af666576c 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -998,12 +998,16 @@ static void trans_drain(struct gfs2_trans *tr)
while (!list_empty(head)) {
bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
list_del_init(&bd->bd_list);
+ if (!list_empty(&bd->bd_ail_st_list))
+ gfs2_remove_from_ail(bd);
kmem_cache_free(gfs2_bufdata_cachep, bd);
}
head = &tr->tr_databuf;
while (!list_empty(head)) {
bd = list_first_entry(head, struct gfs2_bufdata, bd_list);
list_del_init(&bd->bd_list);
+ if (!list_empty(&bd->bd_ail_st_list))
+ gfs2_remove_from_ail(bd);
kmem_cache_free(gfs2_bufdata_cachep, bd);
}
}
diff --git a/fs/gfs2/trans.c b/fs/gfs2/trans.c
index ab96cf0bf26b..63fec11ef2ce 100644
--- a/fs/gfs2/trans.c
+++ b/fs/gfs2/trans.c
@@ -169,6 +169,8 @@ static struct gfs2_bufdata *gfs2_alloc_bufdata(struct gfs2_glock *gl,
bd->bd_bh = bh;
bd->bd_gl = gl;
INIT_LIST_HEAD(&bd->bd_list);
+ INIT_LIST_HEAD(&bd->bd_ail_st_list);
+ INIT_LIST_HEAD(&bd->bd_ail_gl_list);
bh->b_private = bd;
return bd;
}
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