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Subject[PATCH AUTOSEL 3.18 03/19] jffs2: Fix use of uninitialized delayed_work, lockdep breakage
Date
From: Daniel Santos <daniel.santos@pobox.com>

[ Upstream commit a788c5272769ddbcdbab297cf386413eeac04463 ]

jffs2_sync_fs makes the assumption that if CONFIG_JFFS2_FS_WRITEBUFFER
is defined then a write buffer is available and has been initialized.
However, this does is not the case when the mtd device has no
out-of-band buffer:

int jffs2_nand_flash_setup(struct jffs2_sb_info *c)
{
if (!c->mtd->oobsize)
return 0;
...

The resulting call to cancel_delayed_work_sync passing a uninitialized
(but zeroed) delayed_work struct forces lockdep to become disabled.

[ 90.050639] overlayfs: upper fs does not support tmpfile.
[ 90.652264] INFO: trying to register non-static key.
[ 90.662171] the code is fine but needs lockdep annotation.
[ 90.673090] turning off the locking correctness validator.
[ 90.684021] CPU: 0 PID: 1762 Comm: mount_root Not tainted 4.14.63 #0
[ 90.696672] Stack : 00000000 00000000 80d8f6a2 00000038 805f0000 80444600 8fe364f4 805dfbe7
[ 90.713349] 80563a30 000006e2 8068370c 00000001 00000000 00000001 8e2fdc48 ffffffff
[ 90.730020] 00000000 00000000 80d90000 00000000 00000106 00000000 6465746e 312e3420
[ 90.746690] 6b636f6c 03bf0000 f8000000 20676e69 00000000 80000000 00000000 8e2c2a90
[ 90.763362] 80d90000 00000001 00000000 8e2c2a90 00000003 80260dc0 08052098 80680000
[ 90.780033] ...
[ 90.784902] Call Trace:
[ 90.789793] [<8000f0d8>] show_stack+0xb8/0x148
[ 90.798659] [<8005a000>] register_lock_class+0x270/0x55c
[ 90.809247] [<8005cb64>] __lock_acquire+0x13c/0xf7c
[ 90.818964] [<8005e314>] lock_acquire+0x194/0x1dc
[ 90.828345] [<8003f27c>] flush_work+0x200/0x24c
[ 90.837374] [<80041dfc>] __cancel_work_timer+0x158/0x210
[ 90.847958] [<801a8770>] jffs2_sync_fs+0x20/0x54
[ 90.857173] [<80125cf4>] iterate_supers+0xf4/0x120
[ 90.866729] [<80158fc4>] sys_sync+0x44/0x9c
[ 90.875067] [<80014424>] syscall_common+0x34/0x58

Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
Reviewed-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/jffs2/super.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c
index f3194e5147fd..0bbc31d10857 100644
--- a/fs/jffs2/super.c
+++ b/fs/jffs2/super.c
@@ -101,7 +101,8 @@ static int jffs2_sync_fs(struct super_block *sb, int wait)
struct jffs2_sb_info *c = JFFS2_SB_INFO(sb);

#ifdef CONFIG_JFFS2_FS_WRITEBUFFER
- cancel_delayed_work_sync(&c->wbuf_dwork);
+ if (jffs2_is_writebuffered(c))
+ cancel_delayed_work_sync(&c->wbuf_dwork);
#endif

mutex_lock(&c->alloc_sem);
--
2.19.1
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