| Message ID | 20231012230911.48113-2-ricardo@marliere.net |
|---|---|
| State | Accepted |
| Commit | ded85b0c0edd8f45fec88783d7555a5b982449c1 |
| Headers | show |
| Series | media: pvrusb2: fix use after free on context disconnection | expand |
Acked-by: Mike Isely <isely@pobox.com> -Mike On Thu, 12 Oct 2023, Ricardo B. Marliere wrote: > 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-and-tested-by: syzbot+621409285c4156a009b3@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/000000000000a02a4205fff8eb92@google.com/ > Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net> > --- > 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); > } > > >
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); }
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-and-tested-by: syzbot+621409285c4156a009b3@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000a02a4205fff8eb92@google.com/ Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net> --- drivers/media/usb/pvrusb2/pvrusb2-context.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)