From 1a5a2cfd34c17db73c53ef127272c8c1ae220485 Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Thu, 25 Feb 2021 11:11:09 -0500 Subject: [PATCH] gfs2: fix use-after-free in trans_drain 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 Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher --- 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; } -- 2.11.0