>From cf7c3b08f80c4cdb7dd08cb977f29d41efebcf79 Mon Sep 17 00:00:00 2001 From: "Ricardo B. Marliere" Date: Thu, 12 Oct 2023 18:26:47 -0300 Subject: [PATCH] media: pvrusb2: fix use after free on context disconnection Upon module load, a kthread is created targeting the pvr2_context_thread_func function, which may call pvr2_context_destroy and thus call kfree() on the context object. However, that might happen before the usb hub_event handler is able to notify the driver. This patch adds a sanity check before the invalid read reported by syzbot, within the context disconnection call stack. Fixes: e5be15c63804 ("V4L/DVB (7711): pvrusb2: Fix race on module unload") Reported-by: syzbot+621409285c4156a009b3@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000a02a4205fff8eb92@google.com/ Signed-off-by: Ricardo B. Marliere --- drivers/media/usb/pvrusb2/pvrusb2-context.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/media/usb/pvrusb2/pvrusb2-context.c b/drivers/media/usb/pvrusb2/pvrusb2-context.c index 14170a5d72b3..1764674de98b 100644 --- a/drivers/media/usb/pvrusb2/pvrusb2-context.c +++ b/drivers/media/usb/pvrusb2/pvrusb2-context.c @@ -268,7 +268,8 @@ void pvr2_context_disconnect(struct pvr2_context *mp) { pvr2_hdw_disconnect(mp->hdw); mp->disconnect_flag = !0; - pvr2_context_notify(mp); + if (!pvr2_context_shutok()) + pvr2_context_notify(mp); } -- 2.42.0