From: Chengfeng Ye <cyeaa@xxxxxxxxxxxxxx> commit b7c81f80246fac44077166f3e07103affe6db8ff upstream. &e->event and e point to the same address, and &e->event could be freed in queue_event. So there is a potential uaf issue if we dereference e after calling queue_event(). Fix this by adding a temporary variable to maintain e->client in advance, this can avoid the potential uaf issue. Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Chengfeng Ye <cyeaa@xxxxxxxxxxxxxx> Signed-off-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220409041243.603210-2-o-takashi@xxxxxxxxxxxxx Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/firewire/core-cdev.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/firewire/core-cdev.c +++ b/drivers/firewire/core-cdev.c @@ -1480,6 +1480,7 @@ static void outbound_phy_packet_callback { struct outbound_phy_packet_event *e = container_of(packet, struct outbound_phy_packet_event, p); + struct client *e_client; switch (status) { /* expected: */ @@ -1496,9 +1497,10 @@ static void outbound_phy_packet_callback } e->phy_packet.data[0] = packet->timestamp; + e_client = e->client; queue_event(e->client, &e->event, &e->phy_packet, sizeof(e->phy_packet) + e->phy_packet.length, NULL, 0); - client_put(e->client); + client_put(e_client); } static int ioctl_send_phy_packet(struct client *client, union ioctl_arg *arg)
