linux-ext4 - Re: [PATCH v2] misc/fsck.c: Processes may kill other processes.

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Message-ID: <1a96f570-cdb4-35e7-60ad-d1a9d8b03ce4@huawei.com>
Date:   Mon, 17 Oct 2022 11:36:13 +0800
From:   zhanchengbin <zhanchengbin1@...wei.com>
To:     Theodore Ts'o <tytso@....edu>
CC:     <linux-ext4@...r.kernel.org>, Lukas Czerner <lczerner@...hat.com>,
        <liuzhiqiang26@...wei.com>, linfeilong <linfeilong@...wei.com>
Subject: Re: [PATCH v2] misc/fsck.c: Processes may kill other processes.

friendly ping, thanks.

On 2022/10/10 16:56, zhanchengbin wrote:
> I find a error in misc/fsck.c, if run the fsck -N command, processes
> don't execute, just show what would be done. However, the pid whose
> value is -1 is added to the instance_list list in the execute
> function,if the kill_all function is called later, kill(-1, signum)
> is executed, Signals are sent to all processes except the number one
> process and itself. Other processes will be killed if they use the
> default signal processing function.
> 
> Signed-off-by: zhanchengbin <zhanchengbin1@...wei.com>
> Signed-off-by: Lukas Czerner <lczerner@...hat.com>
> ---
> V1->V2:
>    Anything <= 0 is a bug and can have unexpected consequences if
> we actually call the kill(). So change inst->pid==-1 to inst->pid<=0.
> 
>   misc/fsck.c | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/misc/fsck.c b/misc/fsck.c
> index 4efe10ec..c56d1b00 100644
> --- a/misc/fsck.c
> +++ b/misc/fsck.c
> @@ -546,6 +546,8 @@ static int kill_all(int signum)
>       for (inst = instance_list; inst; inst = inst->next) {
>           if (inst->flags & FLAG_DONE)
>               continue;
> +        if (inst->pid <= 0)
> +            continue;
>           kill(inst->pid, signum);
>           n++;
>       }