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From:   David Howells <dhowells@redhat.com>
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To:     syzbot <syzbot+dd1339599f1840e4cc65@syzkaller.appspotmail.com>
Cc:     dhowells@redhat.com, bpf@vger.kernel.org, davem@davemloft.net,
        edumazet@google.com, kuba@kernel.org, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org, pabeni@redhat.com,
        syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [net?] WARNING in unreserve_psock
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Content-ID: <1661017.1686759001.1@warthog.procyon.org.uk>
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Date:   Wed, 14 Jun 2023 17:10:01 +0100
Message-ID: <1661018.1686759001@warthog.procyon.org.uk>
Precedence: bulk

Here's a reduced testcase.

David
---
// https://syzkaller.appspot.com/bug?id=3D6ffe7d1ebf1efaddb7ddd04784b9b22a=
8562b8d0
// autogenerated by syzkaller (https://github.com/google/syzkaller)
#define _GNU_SOURCE
#include <endian.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
#include <linux/kcm.h>

#define OSERROR(R, S) do { if ((long)(R) =3D=3D -1L) { perror((S)); exit(1=
); } } while(0)

int main(void)
{
	struct msghdr msg;
	int kcmfd, res;

	kcmfd =3D socket(AF_KCM, SOCK_DGRAM, KCMPROTO_CONNECTED);
	OSERROR(kcmfd, "socket");

	memset(&msg, 0, sizeof(msg));
	res =3D sendmsg(kcmfd, &msg, 0);
	OSERROR(res, "sendmsg");
	return 0;
}