[PATCH 4.14 58/78] firewire: fix potential uaf in outbound_phy_packet_callback()

Greg Kroah-Hartman
2022-05-10T13:28:54Z

From: Chengfeng Ye <cyeaa@connect.ust.hk>

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@vger.kernel.org>
Signed-off-by: Chengfeng Ye <cyeaa@connect.ust.hk>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20220409041243.603210-2-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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
@@ -1495,6 +1495,7 @@ 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: */
@@ -1511,9 +1512,10 @@ 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)