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

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Date:   Mon, 10 Oct 2022 16:56:58 +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: [PATCH v2] misc/fsck.c: Processes may kill other processes.

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++;
  	}
-- 
2.27.0