From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> stable inclusion from stable-v4.19.256 commit a55ac4419fb75295386e9cd386ab34b62b18e869 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I64WCC CVE: CVE-2022-20566 -------------------------------- commit 332f1795ca202489c665a75e62e18ff6284de077 upstream. The patch d0be8347c623: "Bluetooth: L2CAP: Fix use-after-free caused by l2cap_chan_put" from Jul 21, 2022, leads to the following Smatch static checker warning: net/bluetooth/l2cap_core.c:1977 l2cap_global_chan_by_psm() error: we previously assumed 'c' could be null (see line 1996) Fixes: d0be8347c623 ("Bluetooth: L2CAP: Fix use-after-free caused by l2cap_chan_put") Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Lu Jialin <lujialin4@huawei.com> Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com> Reviewed-by: Wang Weiyang <wangweiyang2@huawei.com> Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com> --- net/bluetooth/l2cap_core.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index 7c2bb0571573..7ac41d375be5 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -1797,11 +1797,11 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm, bdaddr_t *dst, u8 link_type) { - struct l2cap_chan *c, *c1 = NULL; + struct l2cap_chan *c, *tmp, *c1 = NULL; read_lock(&chan_list_lock); - list_for_each_entry(c, &chan_list, global_l) { + list_for_each_entry_safe(c, tmp, &chan_list, global_l) { if (state && c->state != state) continue; @@ -1820,11 +1820,10 @@ static struct l2cap_chan *l2cap_global_chan_by_psm(int state, __le16 psm, dst_match = !bacmp(&c->dst, dst); if (src_match && dst_match) { c = l2cap_chan_hold_unless_zero(c); - if (!c) - continue; - - read_unlock(&chan_list_lock); - return c; + if (c) { + read_unlock(&chan_list_lock); + return c; + } } /* Closest match */ -- 2.25.1