media: pvrusb2: fix array-index-out-of-bounds in pvr2_i2c_core_init

[ Upstream commit 471bec68457aaf981add77b4f590d65dd7da1059 ]

Syzbot reported that -1 is used as array index. The problem was in
missing validation check.

hdw->unit_number is initialized with -1 and then if init table walk fails
this value remains unchanged. Since code blindly uses this member for
array indexing adding sanity check is the easiest fix for that.

hdw->workpoll initialization moved upper to prevent warning in
__flush_work.

Reported-and-tested-by: syzbot+1a247e36149ffd709a9b@syzkaller.appspotmail.com
Fixes: d855497edbfb ("V4L/DVB (4228a): pvrusb2 to kernel 2.6.18")
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/media/usb/pvrusb2/pvrusb2-hdw.c b/drivers/media/usb/pvrusb2/pvrusb2-hdw.c
index 3915d55..fccd179 100644 (file)
--- a/drivers/media/usb/pvrusb2/pvrusb2-hdw.c
+++ b/drivers/media/usb/pvrusb2/pvrusb2-hdw.c
@@ -2569,6 +2569,11 @@ struct pvr2_hdw *pvr2_hdw_create(struct usb_interface *intf,
        } while (0);
        mutex_unlock(&pvr2_unit_mtx);
 
+       INIT_WORK(&hdw->workpoll, pvr2_hdw_worker_poll);
+
+       if (hdw->unit_number == -1)
+               goto fail;
+
        cnt1 = 0;
        cnt2 = scnprintf(hdw->name+cnt1,sizeof(hdw->name)-cnt1,"pvrusb2");
        cnt1 += cnt2;
@@ -2580,8 +2585,6 @@ struct pvr2_hdw *pvr2_hdw_create(struct usb_interface *intf,
        if (cnt1 >= sizeof(hdw->name)) cnt1 = sizeof(hdw->name)-1;
        hdw->name[cnt1] = 0;
 
-       INIT_WORK(&hdw->workpoll,pvr2_hdw_worker_poll);
-
        pvr2_trace(PVR2_TRACE_INIT,"Driver unit number is %d, name is %s",
                   hdw->unit_number,hdw->name);