Re: KASAN: use-after-free Write in rtl_fw_do_work

[Brooke Basile]

On 8/31/20 9:30 AM, Hillf Danton wrote:
> Mon, 31 Aug 2020 04:48:15 -0700
> > syzbot found the following issue on:
> >
> > HEAD commit:    3ed8e1c2 usb: typec: tcpm: Migrate workqueue to RT priorit..
> > git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
> > console output: https://syzkaller.appspot.com/x/log.txt?x=111f9015900000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=ccafc70ac3d5f49c
> > dashboard link: https://syzkaller.appspot.com/bug?extid=dc3cab055dff074f2d7f
> > compiler:       gcc (GCC) 10.1.0-syz 20200507
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=148a00c9900000
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+dc3cab055dff074f2d7f@xxxxxxxxxxxxxxxxxxxxxxxxx
> >
> > usb 1-1: Direct firmware load for rtlwifi/rtl8192cufw_TMSC.bin failed with error -2
> > usb 1-1: Direct firmware load for rtlwifi/rtl8192cufw.bin failed with error -2
> > rtlwifi: Loading alternative firmware rtlwifi/rtl8192cufw.bin
> > rtlwifi: Selected firmware is not available
> > ==================================================================
> > BUG: KASAN: use-after-free in rtl_fw_do_work.cold+0x68/0x6a drivers/net/wireless/realtek/rtlwifi/core.c:93
> > Write of size 4 at addr ffff8881c9c2ff30 by task kworker/1:5/3063
> >
> > CPU: 1 PID: 3063 Comm: kworker/1:5 Not tainted 5.9.0-rc1-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Workqueue: events request_firmware_work_func
> > Call Trace:
> >   __dump_stack lib/dump_stack.c:77 [inline]
> >   dump_stack+0xf6/0x16e lib/dump_stack.c:118
> >   print_address_description.constprop.0+0x1c/0x210 mm/kasan/report.c:383
> >   __kasan_report mm/kasan/report.c:513 [inline]
> >   kasan_report.cold+0x37/0x7c mm/kasan/report.c:530
> >   rtl_fw_do_work.cold+0x68/0x6a drivers/net/wireless/realtek/rtlwifi/core.c:93
> >   request_firmware_work_func+0x126/0x250 drivers/base/firmware_loader/main.c:1001
> >   process_one_work+0x94c/0x15f0 kernel/workqueue.c:2269
> >   worker_thread+0x64c/0x1120 kernel/workqueue.c:2415
> >   kthread+0x392/0x470 kernel/kthread.c:292
> >   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> >
> > The buggy address belongs to the page:
> > page:000000008323bb9d refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1c9c2f
> > flags: 0x200000000000000()
> > raw: 0200000000000000 0000000000000000 ffffea0007270bc8 0000000000000000
> > raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
> > page dumped because: kasan: bad access detected
> >
> > Memory state around the buggy address:
> >   ffff8881c9c2fe00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> >   ffff8881c9c2fe80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > > ffff8881c9c2ff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> >                                       ^
> >   ffff8881c9c2ff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> >   ffff8881c9c30000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
> > ==================================================================
>
>
> While probing pci for instance, wait for kworker to finish its work in the
> err branches.
>
>
> --- a/drivers/net/wireless/realtek/rtlwifi/core.c
> +++ b/drivers/net/wireless/realtek/rtlwifi/core.c
> @@ -78,7 +78,6 @@ static void rtl_fw_do_work(const struct
>   
>   	RT_TRACE(rtlpriv, COMP_ERR, DBG_LOUD,
>   		 "Firmware callback routine entered!\n");
> -	complete(&rtlpriv->firmware_loading_complete);
>   	if (!firmware) {
>   		if (rtlpriv->cfg->alt_fw_name) {
>   			err = request_firmware(&firmware,
> @@ -91,13 +90,12 @@ static void rtl_fw_do_work(const struct
>   		}
>   		pr_err("Selected firmware is not available\n");
>   		rtlpriv->max_fw_size = 0;
> -		return;
> +		goto out;
>   	}
>   found_alt:
>   	if (firmware->size > rtlpriv->max_fw_size) {
>   		pr_err("Firmware is too big!\n");
> -		release_firmware(firmware);
> -		return;
> +		goto release;
>   	}
>   	if (!is_wow) {
>   		memcpy(rtlpriv->rtlhal.pfirmware, firmware->data,
> @@ -108,7 +106,11 @@ found_alt:
>   		       firmware->size);
>   		rtlpriv->rtlhal.wowlan_fwsize = firmware->size;
>   	}
> +
> +release:
>   	release_firmware(firmware);
> +out:
> +	complete(&rtlpriv->firmware_loading_complete);
>   }
>   
>   void rtl_fw_cb(const struct firmware *firmware, void *context)
> --- a/drivers/net/wireless/realtek/rtlwifi/pci.c
> +++ b/drivers/net/wireless/realtek/rtlwifi/pci.c
> @@ -2161,6 +2161,7 @@ int rtl_pci_probe(struct pci_dev *pdev,
>   	struct rtl_pci *rtlpci;
>   	unsigned long pmem_start, pmem_len, pmem_flags;
>   	int err;
> +	bool wait_kworker = false;
>   
>   	err = pci_enable_device(pdev);
>   	if (err) {
> @@ -2272,6 +2273,7 @@ int rtl_pci_probe(struct pci_dev *pdev,
>   		err = -ENODEV;
>   		goto fail3;
>   	}
> +	wait_kworker = true;
>   	rtlpriv->cfg->ops->init_sw_leds(hw);
>   
>   	/*aspm */
> @@ -2327,7 +2329,8 @@ fail2:
>   		pci_iounmap(pdev, (void __iomem *)rtlpriv->io.pci_mem_start);
>   
>   	pci_release_regions(pdev);
> -	complete(&rtlpriv->firmware_loading_complete);
> +	if (wait_kworker == true)
> +		wait_for_completion(&rtlpriv->firmware_loading_complete);
>   
>   fail1:
>   	if (hw)

Hi,

It looks like this is probably a duplicate related to this patch:
https://syzkaller.appspot.com/bug?id=1f05ed98df706bb64aeee4dccc5ab48cd7542643

Best,
Brooke Basile