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| author | YueHaibing <yuehaibing@huawei.com> | 2020-04-28 10:12:08 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-04-28 23:08:59 +0200 |
| commit | 8999dc89497ab1c80d0718828e838c7cd5f6bffe (patch) | |
| tree | 9beed009602bc720ae1e5441d9c2f981565e08cd /net/x25 | |
| parent | net/ena: Fix build warning in ena_xdp_set() (diff) | |
| download | linux-8999dc89497ab1c80d0718828e838c7cd5f6bffe.tar.xz linux-8999dc89497ab1c80d0718828e838c7cd5f6bffe.zip | |
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: 4becb7ee5b3d ("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>
Diffstat (limited to 'net/x25')
| -rw-r--r-- | net/x25/x25_subr.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/net/x25/x25_subr.c b/net/x25/x25_subr.c index 8b1b06cabcbf..0285aaa1e93c 100644 --- a/net/x25/x25_subr.c +++ b/net/x25/x25_subr.c @@ -357,10 +357,12 @@ void x25_disconnect(struct sock *sk, int reason, unsigned char cause, sk->sk_state_change(sk); sock_set_flag(sk, SOCK_DEAD); } - read_lock_bh(&x25_list_lock); - x25_neigh_put(x25->neighbour); - x25->neighbour = NULL; - read_unlock_bh(&x25_list_lock); + if (x25->neighbour) { + read_lock_bh(&x25_list_lock); + x25_neigh_put(x25->neighbour); + x25->neighbour = NULL; + read_unlock_bh(&x25_list_lock); + } } /* |