[PATCH] jffs2: Fix use of uninitialized delayed

Discussion:

[PATCH] jffs2: Fix use of uninitialized delayed_work, lockdep breakage

Daniel Santos

2018-10-19 08:30:20 UTC

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 <***@pobox.com>
---
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 793ad30970ff..cae4ecda3c50 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);

--
2.16.4

Hou Tao

2018-10-22 00:32:52 UTC

Permalink

Post by Daniel Santos
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
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] ...
[ 90.789793] [<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
---
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 793ad30970ff..cae4ecda3c50 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);

Reviewed-by: Hou Tao <***@huawei.com>

And I am curious that why is there NAND Flash without OOB area ? So for them
the ECC data must be saved in data area ?

Regards,

Tao

Daniel Santos

2018-10-22 04:56:45 UTC

Permalink

Post by Hou Tao

And I am curious that why is there NAND Flash without OOB area ? So for them
the ECC data must be saved in data area ?
Regards,
Tao

Thank you.

I'm not intimately familiar with these, but it's an SPI NOR chip and I'm
pretty sure they that they don't have ECC. Specifically a Winbond
w25q128fv using drivers/mtd/devices/m25p80.c.

Thanks,
Daniel

Daniel Santos

2018-11-05 21:38:49 UTC

Permalink

Ping.

Daniel

Post by Hou Tao