From: jouni.hogander@unikie•com (Jouni Högander)
To: netdev@vger•kernel.org
Cc: David Miller <davem@davemloft•net>,
Oliver Hartkopp <socketcan@hartkopp•net>,
Lukas Bulwahn <lukas.bulwahn@gmail•com>
Subject: Re: [PATCH] slip: Fix use-after-free Read in slip_open
Date: Mon, 25 Nov 2019 14:28:14 +0200 [thread overview]
Message-ID: <87sgmcqgwx.fsf@unikie.com> (raw)
In-Reply-To: <20191125122343.17904-1-jouni.hogander@unikie.com> (jouni hogander's message of "Mon, 25 Nov 2019 14:23:43 +0200")
jouni.hogander@unikie•com writes:
> From: Jouni Hogander <jouni.hogander@unikie•com>
>
> Slip_open doesn't clean-up device which registration failed from the
> slip_devs device list. On next open after failure this list is iterated
> and freed device is accessed. Fix this by calling sl_free_netdev in error
> path.
>
> Here is the trace from the Syzbot:
>
> __dump_stack lib/dump_stack.c:77 [inline]
> dump_stack+0x197/0x210 lib/dump_stack.c:118
> print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
> __kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
> kasan_report+0x12/0x20 mm/kasan/common.c:634
> __asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
> sl_sync drivers/net/slip/slip.c:725 [inline]
> slip_open+0xecd/0x11b7 drivers/net/slip/slip.c:801
> tty_ldisc_open.isra.0+0xa3/0x110 drivers/tty/tty_ldisc.c:469
> tty_set_ldisc+0x30e/0x6b0 drivers/tty/tty_ldisc.c:596
> tiocsetd drivers/tty/tty_io.c:2334 [inline]
> tty_ioctl+0xe8d/0x14f0 drivers/tty/tty_io.c:2594
> vfs_ioctl fs/ioctl.c:46 [inline]
> file_ioctl fs/ioctl.c:509 [inline]
> do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
> ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
> __do_sys_ioctl fs/ioctl.c:720 [inline]
> __se_sys_ioctl fs/ioctl.c:718 [inline]
> __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
> do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Fixes: 3b5a39979daf ("slip: Fix memory leak in slip_open error path")
> Reported-by: syzbot+4d5170758f3762109542@syzkaller•appspotmail.com
Unfortunately I'm not able to reproduce this by myself. But to my
understanding scenario described above is possible path to this
use-after-free bug.
> Cc: David Miller <davem@davemloft•net>
> Cc: Oliver Hartkopp <socketcan@hartkopp•net>
> Cc: Lukas Bulwahn <lukas.bulwahn@gmail•com>
> Signed-off-by: Jouni Hogander <jouni.hogander@unikie•com>
> ---
> drivers/net/slip/slip.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/slip/slip.c b/drivers/net/slip/slip.c
> index 4d479e3c817d..2a91c192659f 100644
> --- a/drivers/net/slip/slip.c
> +++ b/drivers/net/slip/slip.c
> @@ -855,6 +855,7 @@ static int slip_open(struct tty_struct *tty)
> sl->tty = NULL;
> tty->disc_data = NULL;
> clear_bit(SLF_INUSE, &sl->flags);
> + sl_free_netdev(sl->dev);
> free_netdev(sl->dev);
>
> err_exit:
BR,
Jouni Högander
next prev parent reply other threads:[~2019-11-25 12:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-25 12:23 [PATCH] slip: Fix use-after-free Read in slip_open jouni.hogander
2019-11-25 12:28 ` Jouni Högander [this message]
2019-11-27 6:27 ` Lukas Bulwahn
2019-11-25 19:03 ` David Miller
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