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

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Message-ID: <Y0QyzHbcnBrUBlkP@magnolia>
Date:   Mon, 10 Oct 2022 07:57:16 -0700
From:   "Darrick J. Wong" <djwong@...nel.org>
To:     zhanchengbin <zhanchengbin1@...wei.com>
Cc:     Theodore Ts'o <tytso@....edu>, 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.

On Mon, Oct 10, 2022 at 04:56:58PM +0800, 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>

Looks good to me,
Reviewed-by: Darrick J. Wong <djwong@...nel.org>

Ted: Perhaps it's time to retire fsck.c in the e2fsprogs distribution?

--D

> ---
> 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++;
>  	}
> -- 
> 2.27.0
>