* [PATCH 0/2] ubifs: Fix two bugs in tnc
@ 2022-11-18 9:02 Zhihao Cheng
2022-11-18 9:02 ` [PATCH 1/2] ubifs: Re-statistic cleaned znode count if commit failed Zhihao Cheng
2022-11-18 9:02 ` [PATCH 2/2] ubifs: dirty_cow_znode: Fix memleak in error handling path Zhihao Cheng
0 siblings, 2 replies; 3+ messages in thread
From: Zhihao Cheng @ 2022-11-18 9:02 UTC (permalink / raw)
To: richard, miquel.raynal, s.hauer
Cc: linux-mtd, linux-kernel, chengzhihao1, yi.zhang
Zhihao Cheng (2):
ubifs: Re-statistic cleaned znode count if commit failed
ubifs: dirty_cow_znode: Fix memleak in error handling path
fs/ubifs/tnc.c | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
--
2.31.1
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH 1/2] ubifs: Re-statistic cleaned znode count if commit failed
2022-11-18 9:02 [PATCH 0/2] ubifs: Fix two bugs in tnc Zhihao Cheng
@ 2022-11-18 9:02 ` Zhihao Cheng
2022-11-18 9:02 ` [PATCH 2/2] ubifs: dirty_cow_znode: Fix memleak in error handling path Zhihao Cheng
1 sibling, 0 replies; 3+ messages in thread
From: Zhihao Cheng @ 2022-11-18 9:02 UTC (permalink / raw)
To: richard, miquel.raynal, s.hauer
Cc: linux-mtd, linux-kernel, chengzhihao1, yi.zhang
Dirty znodes will be written on flash in committing process with
following states:
process A | znode state
------------------------------------------------------
do_commit | DIRTY_ZNODE
ubifs_tnc_start_commit | DIRTY_ZNODE
get_znodes_to_commit | DIRTY_ZNODE | COW_ZNODE
layout_commit | DIRTY_ZNODE | COW_ZNODE
fill_gap | 0
write master | 0 or OBSOLETE_ZNODE
process B | znode state
------------------------------------------------------
do_commit | DIRTY_ZNODE[1]
ubifs_tnc_start_commit | DIRTY_ZNODE
get_znodes_to_commit | DIRTY_ZNODE | COW_ZNODE
ubifs_tnc_end_commit | DIRTY_ZNODE | COW_ZNODE
write_index | 0
write master | 0 or OBSOLETE_ZNODE[2] or
| DIRTY_ZNODE[3]
[1] znode is dirtied without concurrent committing process
[2] znode is copied up (re-dirtied by other process) before cleaned
up in committing process
[3] znode is re-dirtied after cleaned up in committing process
Currently, the clean znode count is updated in free_obsolete_znodes(),
which is called only in normal path. If do_commit failed, clean znode
count won't be updated, which triggers a failure ubifs assertion[4] in
ubifs_tnc_close():
ubifs_assert_failed [ubifs]: UBIFS assert failed: freed == n
[4] Commit 380347e9ca7682 ("UBIFS: Add an assertion for clean_zn_cnt").
Fix it by re-statisticing cleaned znode count in tnc_destroy_cnext().
Fetch a reproducer in [Link].
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216704
Fixes: 1e51764a3c2a ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
fs/ubifs/tnc.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 488f3da7a6c6..2df56bbc6865 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -3053,6 +3053,21 @@ static void tnc_destroy_cnext(struct ubifs_info *c)
cnext = cnext->cnext;
if (ubifs_zn_obsolete(znode))
kfree(znode);
+ else if (!ubifs_zn_cow(znode)) {
+ /*
+ * Don't forget to update clean znode count after
+ * committing failed, because ubifs will check this
+ * count while closing tnc. Non-obsolete znode could
+ * be re-dirtied during committing process, so dirty
+ * flag is untrustable. The flag 'COW_ZNODE' is set
+ * for each dirty znode before committing, and it is
+ * cleared as long as the znode become clean, so we
+ * can statistic clean znode count according to this
+ * flag.
+ */
+ atomic_long_inc(&c->clean_zn_cnt);
+ atomic_long_inc(&ubifs_clean_zn_cnt);
+ }
} while (cnext && cnext != c->cnext);
}
--
2.31.1
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 2/2] ubifs: dirty_cow_znode: Fix memleak in error handling path
2022-11-18 9:02 [PATCH 0/2] ubifs: Fix two bugs in tnc Zhihao Cheng
2022-11-18 9:02 ` [PATCH 1/2] ubifs: Re-statistic cleaned znode count if commit failed Zhihao Cheng
@ 2022-11-18 9:02 ` Zhihao Cheng
1 sibling, 0 replies; 3+ messages in thread
From: Zhihao Cheng @ 2022-11-18 9:02 UTC (permalink / raw)
To: richard, miquel.raynal, s.hauer
Cc: linux-mtd, linux-kernel, chengzhihao1, yi.zhang
Following process will cause a memleak for copied up znode:
dirty_cow_znode
zn = copy_znode(c, znode);
err = insert_old_idx(c, zbr->lnum, zbr->offs);
if (unlikely(err))
return ERR_PTR(err); // No one refers to zn.
Fix it by adding copied znode back to tnc, then it will be freed
by ubifs_destroy_tnc_subtree() while closing tnc.
Fetch a reproducer in [Link].
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216705
Fixes: 1e51764a3c2a ("UBIFS: add new flash file system")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
fs/ubifs/tnc.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 2df56bbc6865..2469f72eeaab 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -267,11 +267,18 @@ static struct ubifs_znode *dirty_cow_znode(struct ubifs_info *c,
if (zbr->len) {
err = insert_old_idx(c, zbr->lnum, zbr->offs);
if (unlikely(err))
- return ERR_PTR(err);
+ /*
+ * Obsolete znodes will be freed by tnc_destroy_cnext()
+ * or free_obsolete_znodes(), copied up znodes should
+ * be added back to tnc and freed by
+ * ubifs_destroy_tnc_subtree().
+ */
+ goto out;
err = add_idx_dirt(c, zbr->lnum, zbr->len);
} else
err = 0;
+out:
zbr->znode = zn;
zbr->lnum = 0;
zbr->offs = 0;
--
2.31.1
______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/
^ permalink raw reply related [flat|nested] 3+ messages in thread
end of thread, other threads:[~2022-11-18 8:41 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-11-18 9:02 [PATCH 0/2] ubifs: Fix two bugs in tnc Zhihao Cheng
2022-11-18 9:02 ` [PATCH 1/2] ubifs: Re-statistic cleaned znode count if commit failed Zhihao Cheng
2022-11-18 9:02 ` [PATCH 2/2] ubifs: dirty_cow_znode: Fix memleak in error handling path Zhihao Cheng
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).