Re: WARNING: Support for this device (Terratec Grabster AV400) is experimental.

[Andrey Konovalov]

On Tue, Apr 30, 2019 at 4:36 PM syzbot
<syzbot+af8f8d2ac0d39b0ed3a0@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    9a33b369 usb-fuzzer: main usb gadget fuzzer driver
> git tree:       https://github.com/google/kasan.git usb-fuzzer
> console output: https://syzkaller.appspot.com/x/log.txt?x=141ca62d200000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=23e37f59d94ddd15
> dashboard link: https://syzkaller.appspot.com/bug?extid=af8f8d2ac0d39b0ed3a0
> compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1405bedd200000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13ce3bbb200000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+af8f8d2ac0d39b0ed3a0@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> usb 1-1: New USB device found, idVendor=0ccd, idProduct=0039, bcdDevice=
> d.3c
> usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
> usb 1-1: config 0 descriptor??
> pvrusb2: Hardware description: Terratec Grabster AV400
> pvrusb2: **********
> pvrusb2: WARNING: Support for this device (Terratec Grabster AV400) is
> experimental.
> pvrusb2: Important functionality might not be entirely working.
> pvrusb2: Please consider contacting the driver author to help with further
> stabilization of the driver.
> pvrusb2: **********

#syz test: https://github.com/google/kasan.git usb-fuzzer

>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches
commit f15cfa809ec035eebc0bec07bc9e1dd2123281a5
Author: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Date:   Wed Apr 17 19:40:40 2019 +0200

    media: pvrusb2: use a different format for warnings
    
    When the pvrusb2 driver detects that there's something wrong with the
    device, it prints a warning message. Right now those message are printed
    in two different formats:
    
    1. ***WARNING*** message here
    2. WARNING: message here
    
    There's an issue with the second format. Syzkaller recognizes it as a
    message produced by a WARN_ON(), which is used to indicate a bug in the
    kernel. However pvrusb2 prints those warnings to indicate an issue with
    the device, not the bug in the kernel.
    
    This patch changes the pvrusb2 driver to consistently use the first
    warning message format. This will unblock syzkaller testing of this
    driver.
    
    Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>

diff --git a/drivers/media/usb/pvrusb2/pvrusb2-hdw.c b/drivers/media/usb/pvrusb2/pvrusb2-hdw.c
index 446a999dd2ce..a0f7b10045d2 100644
--- a/drivers/media/usb/pvrusb2/pvrusb2-hdw.c
+++ b/drivers/media/usb/pvrusb2/pvrusb2-hdw.c
@@ -1678,7 +1678,7 @@ static int pvr2_decoder_enable(struct pvr2_hdw *hdw,int enablefl)
 	}
 	if (!hdw->flag_decoder_missed) {
 		pvr2_trace(PVR2_TRACE_ERROR_LEGS,
-			   "WARNING: No decoder present");
+			   "***WARNING*** No decoder present");
 		hdw->flag_decoder_missed = !0;
 		trace_stbit("flag_decoder_missed",
 			    hdw->flag_decoder_missed);
@@ -2364,7 +2364,7 @@ struct pvr2_hdw *pvr2_hdw_create(struct usb_interface *intf,
 	if (hdw_desc->flag_is_experimental) {
 		pvr2_trace(PVR2_TRACE_INFO, "**********");
 		pvr2_trace(PVR2_TRACE_INFO,
-			   "WARNING: Support for this device (%s) is experimental.",
+			   "***WARNING*** Support for this device (%s) is experimental.",
 							      hdw_desc->description);
 		pvr2_trace(PVR2_TRACE_INFO,
 			   "Important functionality might not be entirely working.");
diff --git a/drivers/media/usb/pvrusb2/pvrusb2-i2c-core.c b/drivers/media/usb/pvrusb2/pvrusb2-i2c-core.c
index 8f023085c2d9..43e54bdbd4aa 100644
--- a/drivers/media/usb/pvrusb2/pvrusb2-i2c-core.c
+++ b/drivers/media/usb/pvrusb2/pvrusb2-i2c-core.c
@@ -343,11 +343,11 @@ static int i2c_hack_cx25840(struct pvr2_hdw *hdw,
 
 	if ((ret != 0) || (*rdata == 0x04) || (*rdata == 0x0a)) {
 		pvr2_trace(PVR2_TRACE_ERROR_LEGS,
-			   "WARNING: Detected a wedged cx25840 chip; the device will not work.");
+			   "***WARNING*** Detected a wedged cx25840 chip; the device will not work.");
 		pvr2_trace(PVR2_TRACE_ERROR_LEGS,
-			   "WARNING: Try power cycling the pvrusb2 device.");
+			   "***WARNING*** Try power cycling the pvrusb2 device.");
 		pvr2_trace(PVR2_TRACE_ERROR_LEGS,
-			   "WARNING: Disabling further access to the device to prevent other foul-ups.");
+			   "***WARNING*** Disabling further access to the device to prevent other foul-ups.");
 		// This blocks all further communication with the part.
 		hdw->i2c_func[0x44] = NULL;
 		pvr2_hdw_render_useless(hdw);
diff --git a/drivers/media/usb/pvrusb2/pvrusb2-std.c b/drivers/media/usb/pvrusb2/pvrusb2-std.c
index 6b651f8b54df..37dc299a1ca2 100644
--- a/drivers/media/usb/pvrusb2/pvrusb2-std.c
+++ b/drivers/media/usb/pvrusb2/pvrusb2-std.c
@@ -353,7 +353,7 @@ struct v4l2_standard *pvr2_std_create_enum(unsigned int *countptr,
 		bcnt = pvr2_std_id_to_str(buf,sizeof(buf),fmsk);
 		pvr2_trace(
 			PVR2_TRACE_ERROR_LEGS,
-			"WARNING: Failed to classify the following standard(s): %.*s",
+			"***WARNING*** Failed to classify the following standard(s): %.*s",
 			bcnt,buf);
 	}