linux-kernel - Re: [PATCH AUTOSEL 4.19 33/57] blk-mq: protect debugfs_create

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Date:   Wed, 3 Apr 2019 12:17:17 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux-block@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 4.19 33/57] blk-mq: protect
 debugfs_create_files() from failures

On Sat, Mar 30, 2019 at 06:43:11AM +0100, Greg Kroah-Hartman wrote:
>On Fri, Mar 29, 2019 at 09:28:26PM -0400, Sasha Levin wrote:
>> From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>>
>> [ Upstream commit 36991ca68db9dd43bac7f3519f080ee3939263ef ]
>>
>> If debugfs were to return a non-NULL error for a debugfs call, using
>> that pointer later in debugfs_create_files() would crash.
>>
>> Fix that by properly checking the pointer before referencing it.
>>
>> Reported-by: Michal Hocko <mhocko@...nel.org>
>> Reported-and-tested-by: syzbot+b382ba6a802a3d242790@...kaller.appspotmail.com
>> Reported-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
>> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> Signed-off-by: Sasha Levin <sashal@...nel.org>
>> ---
>>  block/blk-mq-debugfs.c | 3 +++
>>  1 file changed, 3 insertions(+)
>>
>> diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
>> index cb1e6cf7ac48..9dc3a0896462 100644
>> --- a/block/blk-mq-debugfs.c
>> +++ b/block/blk-mq-debugfs.c
>> @@ -806,6 +806,9 @@ static const struct blk_mq_debugfs_attr blk_mq_debugfs_ctx_attrs[] = {
>>  static bool debugfs_create_files(struct dentry *parent, void *data,
>>  				 const struct blk_mq_debugfs_attr *attr)
>>  {
>> +	if (IS_ERR_OR_NULL(parent))
>> +		return false;
>> +
>>  	d_inode(parent)->i_private = data;
>>
>>  	for (; attr->name; attr++) {
>> --
>> 2.19.1
>>
>
>This was a 5.0-only thing, no need for it to be backported anywhere.
>Please drop it from all of your trees.

Dropped, thanks.

--
Thanks,
Sasha