On 8/31/20 7:56 PM, Hillf Danton wrote:

On Mon, 31 Aug 2020 15:15:13 -0400 Brooke Basile wrote:

quoted

On 8/31/20 9:30 AM, Hillf Danton wrote:

quoted

Mon, 31 Aug 2020 04:48:15 -0700

quoted

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@syzkaller.appspotmail.com

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

quoted

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,

Hi Brooke

quoted

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

Quite likely, particularly for the accesses to the link above in the
far east cities like Shanghai. More interesting may be that we can see
the difference between the two patches if you can copy-n-paste that
one in reply to this message because I have no clear idea if it's the
ad hoc matter of fact that fixes for syzbot reports should better be
posted in the report mail thread at lore.kernel.org, with the
ant-anntena-size bonus to facilitate those who are disabled outside
lore in the split of a second.

Sorry, in hindsight my wording may have been a bit awkward in my 
message-- what I meant to say is, your patch may also resolve that bug. :)
I don't actually have a patch for this, I had just begun working on it 
over the weekend and saw that your patch could be related to the issue.

Best,
Brooke Basile