2022-04-11 11:02:48

by Jiri Slaby

Subject: Re: [PATCH] tty: synclink_gt: Fix null-pointer-dereference in slgt_clean()

On 10. 04. 22, 13:48, Zheyu Ma wrote:
> When the driver fails at alloc_hdlcdev(), and then we remove the driver
> module, we will get the following splat:
>
> [ 25.065966] general protection fault, probably for non-canonical address 0xdffffc0000000182: 0000 [#1] PREEMPT SMP KASAN PTI
> [ 25.066914] KASAN: null-ptr-deref in range [0x0000000000000c10-0x0000000000000c17]
> [ 25.069262] RIP: 0010:detach_hdlc_protocol+0x2a/0x3e0
> [ 25.077709] Call Trace:
> [ 25.077924] <TASK>
> [ 25.078108] unregister_hdlc_device+0x16/0x30
> [ 25.078481] slgt_cleanup+0x157/0x9f0 [synclink_gt]
>
> Fix this by checking whether the 'info->netdev' is a null pointer first.

Hi,

LGTM

Reviewed-by: Jiri Slaby <[email protected]>

Out of curiosity, do you use the driver, or you only do some static
analysis?

> Signed-off-by: Zheyu Ma <[email protected]>
> ---
> drivers/tty/synclink_gt.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c
> index 25c558e65ece..9bc2a9265277 100644
> --- a/drivers/tty/synclink_gt.c
> +++ b/drivers/tty/synclink_gt.c
> @@ -1746,6 +1746,8 @@ static int hdlcdev_init(struct slgt_info *info)
> */
> static void hdlcdev_exit(struct slgt_info *info)
> {
> + if (!info->netdev)
> + return;
> unregister_hdlc_device(info->netdev);
> free_netdev(info->netdev);
> info->netdev = NULL;


--
js
suse labs

2022-04-12 22:45:13

by Zheyu Ma

Subject: Re: [PATCH] tty: synclink_gt: Fix null-pointer-dereference in slgt_clean()

On Mon, Apr 11, 2022 at 6:13 PM Jiri Slaby <[email protected]> wrote:
>
> On 10. 04. 22, 13:48, Zheyu Ma wrote:
> > When the driver fails at alloc_hdlcdev(), and then we remove the driver
> > module, we will get the following splat:
> >
> > [ 25.065966] general protection fault, probably for non-canonical address 0xdffffc0000000182: 0000 [#1] PREEMPT SMP KASAN PTI
> > [ 25.066914] KASAN: null-ptr-deref in range [0x0000000000000c10-0x0000000000000c17]
> > [ 25.069262] RIP: 0010:detach_hdlc_protocol+0x2a/0x3e0
> > [ 25.077709] Call Trace:
> > [ 25.077924] <TASK>
> > [ 25.078108] unregister_hdlc_device+0x16/0x30
> > [ 25.078481] slgt_cleanup+0x157/0x9f0 [synclink_gt]
> >
> > Fix this by checking whether the 'info->netdev' is a null pointer first.
>
> Hi,
>
> LGTM
>
> Reviewed-by: Jiri Slaby <[email protected]>
>
> Out of curiosity, do you use the driver, or you only do some static
> analysis?

In fact, neither. I test the driver via fuzzing in a simulated environment.

Zheyu Ma