On 21-07-31 00:44:11, Pavel Skripkin wrote:
> Syzbot reported uninit value pegasus_probe(). The problem was in missing
> error handling.
>
> get_interrupt_interval() internally calls read_eprom_word() which can
> fail in some cases. For example: failed to receive usb control message.
> These cases should be handled to prevent uninit value bug, since
> read_eprom_word() will not initialize passed stack variable in case of
> internal failure.
Well, this is most definitelly a bug.
ACK!
Petko
> Fail log:
>
> BUG: KMSAN: uninit-value in get_interrupt_interval drivers/net/usb/pegasus.c:746 [inline]
> BUG: KMSAN: uninit-value in pegasus_probe+0x10e7/0x4080 drivers/net/usb/pegasus.c:1152
> CPU: 1 PID: 825 Comm: kworker/1:1 Not tainted 5.12.0-rc6-syzkaller #0
> ...
> Workqueue: usb_hub_wq hub_event
> Call Trace:
> __dump_stack lib/dump_stack.c:79 [inline]
> dump_stack+0x24c/0x2e0 lib/dump_stack.c:120
> kmsan_report+0xfb/0x1e0 mm/kmsan/kmsan_report.c:118
> __msan_warning+0x5c/0xa0 mm/kmsan/kmsan_instr.c:197
> get_interrupt_interval drivers/net/usb/pegasus.c:746 [inline]
> pegasus_probe+0x10e7/0x4080 drivers/net/usb/pegasus.c:1152
> ....
>
> Local variable ----data.i@pegasus_probe created at:
> get_interrupt_interval drivers/net/usb/pegasus.c:1151 [inline]
> pegasus_probe+0xe57/0x4080 drivers/net/usb/pegasus.c:1152
> get_interrupt_interval drivers/net/usb/pegasus.c:1151 [inline]
> pegasus_probe+0xe57/0x4080 drivers/net/usb/pegasus.c:1152
>
> Reported-and-tested-by: syzbot+02c9f70f3afae308464a@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx>
> ---
> drivers/net/usb/pegasus.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c
> index 9a907182569c..bc2dbf86496b 100644
> --- a/drivers/net/usb/pegasus.c
> +++ b/drivers/net/usb/pegasus.c
> @@ -735,12 +735,16 @@ static inline void disable_net_traffic(pegasus_t *pegasus)
> set_registers(pegasus, EthCtrl0, sizeof(tmp), &tmp);
> }
>
> -static inline void get_interrupt_interval(pegasus_t *pegasus)
> +static inline int get_interrupt_interval(pegasus_t *pegasus)
> {
> u16 data;
> u8 interval;
> + int ret;
> +
> + ret = read_eprom_word(pegasus, 4, &data);
> + if (ret < 0)
> + return ret;
>
> - read_eprom_word(pegasus, 4, &data);
> interval = data >> 8;
> if (pegasus->usb->speed != USB_SPEED_HIGH) {
> if (interval < 0x80) {
> @@ -755,6 +759,8 @@ static inline void get_interrupt_interval(pegasus_t *pegasus)
> }
> }
> pegasus->intr_interval = interval;
> +
> + return 0;
> }
>
> static void set_carrier(struct net_device *net)
> @@ -1149,7 +1155,9 @@ static int pegasus_probe(struct usb_interface *intf,
> | NETIF_MSG_PROBE | NETIF_MSG_LINK);
>
> pegasus->features = usb_dev_id[dev_index].private;
> - get_interrupt_interval(pegasus);
> + res = get_interrupt_interval(pegasus);
> + if (res)
> + goto out2;
> if (reset_mac(pegasus)) {
> dev_err(&intf->dev, "can't reset MAC\n");
> res = -EIO;
> --
> 2.32.0
>
>
