From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/bluetooth/l2cap_core.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -1804,11 +1804,11 @@ static struct l2cap_chan *l2cap_global_c
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;
@@ -1827,11 +1827,10 @@ static struct l2cap_chan *l2cap_global_c
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 */
