linux/net/x25
YueHaibing 8999dc8949 net/x25: Fix null-ptr-deref in x25_disconnect
We should check null before do x25_neigh_put in x25_disconnect,
otherwise may cause null-ptr-deref like this:

 #include <sys/socket.h>
 #include <linux/x25.h>

 int main() {
    int sck_x25;
    sck_x25 = socket(AF_X25, SOCK_SEQPACKET, 0);
    close(sck_x25);
    return 0;
 }

BUG: kernel NULL pointer dereference, address: 00000000000000d8
CPU: 0 PID: 4817 Comm: t2 Not tainted 5.7.0-rc3+ #159
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-
RIP: 0010:x25_disconnect+0x91/0xe0
Call Trace:
 x25_release+0x18a/0x1b0
 __sock_release+0x3d/0xc0
 sock_close+0x13/0x20
 __fput+0x107/0x270
 ____fput+0x9/0x10
 task_work_run+0x6d/0xb0
 exit_to_usermode_loop+0x102/0x110
 do_syscall_64+0x23c/0x260
 entry_SYSCALL_64_after_hwframe+0x49/0xb3

Reported-by: syzbot+6db548b615e5aeefdce2@syzkaller.appspotmail.com
Fixes: 4becb7ee5b ("net/x25: Fix x25_neigh refcnt leak when x25 disconnect")
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-04-28 14:08:59 -07:00
..
af_x25.c net/x25: fix nonblocking connect 2020-01-09 18:39:33 -08:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
sysctl_net_x25.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
x25_dev.c net/x25: Fix x25_neigh refcnt leak when receiving frame 2020-04-23 15:39:39 -07:00
x25_facilities.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 41 2019-05-24 17:27:12 +02:00
x25_forward.c net: x25: convert to list_for_each_entry_safe() 2020-02-16 18:59:42 -08:00
x25_in.c net/x25: add new state X25_STATE_5 2019-12-09 10:28:43 -08:00
x25_link.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 41 2019-05-24 17:27:12 +02:00
x25_out.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 41 2019-05-24 17:27:12 +02:00
x25_proc.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 41 2019-05-24 17:27:12 +02:00
x25_route.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 41 2019-05-24 17:27:12 +02:00
x25_subr.c net/x25: Fix null-ptr-deref in x25_disconnect 2020-04-28 14:08:59 -07:00
x25_timer.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 41 2019-05-24 17:27:12 +02:00