2019-07-26 03:38:20

by Jia-Ju Bai

Subject: [PATCH 2/3] fs: ocfs2: Fix a possible null-pointer dereference in ocfs2_write_end_nolock()

In ocfs2_write_end_nolock(), there are an if statement on lines 1976,
2047 and 2058, to check whether handle is NULL:
if (handle)

When handle is NULL, it is used on line 2045:
ocfs2_update_inode_fsync_trans(handle, inode, 1);
oi->i_sync_tid = handle->h_transaction->t_tid;

Thus, a possible null-pointer dereference may occur.

To fix this bug, handle is checked before calling
ocfs2_update_inode_fsync_trans().

This bug is found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <[email protected]>
---
fs/ocfs2/aops.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index a4c905d6b575..5473bd99043e 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -2042,7 +2042,8 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
inode->i_mtime = inode->i_ctime = current_time(inode);
di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
- ocfs2_update_inode_fsync_trans(handle, inode, 1);
+ if (handle)
+ ocfs2_update_inode_fsync_trans(handle, inode, 1);
}
if (handle)
ocfs2_journal_dirty(handle, wc->w_di_bh);
--
2.17.0

2019-07-26 09:39:08

by Joseph Qi

Subject: Re: [PATCH 2/3] fs: ocfs2: Fix a possible null-pointer dereference in ocfs2_write_end_nolock()

On 19/7/26 11:37, Jia-Ju Bai wrote:
> In ocfs2_write_end_nolock(), there are an if statement on lines 1976,
> 2047 and 2058, to check whether handle is NULL:
> if (handle)
>
> When handle is NULL, it is used on line 2045:
> ocfs2_update_inode_fsync_trans(handle, inode, 1);
> oi->i_sync_tid = handle->h_transaction->t_tid;
>
> Thus, a possible null-pointer dereference may occur.
>
> To fix this bug, handle is checked before calling
> ocfs2_update_inode_fsync_trans().
>
> This bug is found by a static analysis tool STCheck written by us.
>
> Signed-off-by: Jia-Ju Bai <[email protected]>

Looks good.
Reviewed-by: Joseph Qi <[email protected]>

> ---
> fs/ocfs2/aops.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
> index a4c905d6b575..5473bd99043e 100644
> --- a/fs/ocfs2/aops.c
> +++ b/fs/ocfs2/aops.c
> @@ -2042,7 +2042,8 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
> inode->i_mtime = inode->i_ctime = current_time(inode);
> di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
> di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
> - ocfs2_update_inode_fsync_trans(handle, inode, 1);
> + if (handle)
> + ocfs2_update_inode_fsync_trans(handle, inode, 1);
> }
> if (handle)
> ocfs2_journal_dirty(handle, wc->w_di_bh);
>

2019-08-05 02:40:28

by Changwei Ge

Subject: Re: [Ocfs2-devel] [PATCH 2/3] fs: ocfs2: Fix a possible null-pointer dereference in ocfs2_write_end_nolock()

Hi Jia-ju,


Could you please point out how ->w_handle can be NULL if we are changing
disk inode?

I just checked the ocfs2 code but can't find any clue ...

In my opinion, it's impossible to change disk inode without an existed
journal transaction. If truly so, it's a another problem.


Thanks,

Changwei


On 2019/7/26 5:38 下午, Joseph Qi wrote:
>
> On 19/7/26 11:37, Jia-Ju Bai wrote:
>> In ocfs2_write_end_nolock(), there are an if statement on lines 1976,
>> 2047 and 2058, to check whether handle is NULL:
>> if (handle)
>>
>> When handle is NULL, it is used on line 2045:
>> ocfs2_update_inode_fsync_trans(handle, inode, 1);
>> oi->i_sync_tid = handle->h_transaction->t_tid;
>>
>> Thus, a possible null-pointer dereference may occur.
>>
>> To fix this bug, handle is checked before calling
>> ocfs2_update_inode_fsync_trans().
>>
>> This bug is found by a static analysis tool STCheck written by us.
>>
>> Signed-off-by: Jia-Ju Bai <[email protected]>
> Looks good.
> Reviewed-by: Joseph Qi <[email protected]>
>
>> ---
>> fs/ocfs2/aops.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
>> index a4c905d6b575..5473bd99043e 100644
>> --- a/fs/ocfs2/aops.c
>> +++ b/fs/ocfs2/aops.c
>> @@ -2042,7 +2042,8 @@ int ocfs2_write_end_nolock(struct address_space *mapping,
>> inode->i_mtime = inode->i_ctime = current_time(inode);
>> di->i_mtime = di->i_ctime = cpu_to_le64(inode->i_mtime.tv_sec);
>> di->i_mtime_nsec = di->i_ctime_nsec = cpu_to_le32(inode->i_mtime.tv_nsec);
>> - ocfs2_update_inode_fsync_trans(handle, inode, 1);
>> + if (handle)
>> + ocfs2_update_inode_fsync_trans(handle, inode, 1);
>> }
>> if (handle)
>> ocfs2_journal_dirty(handle, wc->w_di_bh);
>>
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