On 01/20/2014 04:43 PM, Michael S. Tsirkin wrote: > On Sun, Jan 19, 2014 at 07:48:56PM -0800, David Miller wrote: >> From: Jason Wang <jasowang@xxxxxxxxxx> >> Date: Mon, 20 Jan 2014 11:16:48 +0800 >> >>> This patch return the error code of copy helpers in tun_put_user() instead of >>> ignoring them. >>> >>> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx> >>> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> > I'm not sure we need to worry about this too much. > But if yes, a bunch of places besides tun should be > changed. Yes, I send the patch because the error processing here is different from what macvtap does. Macvtap just return error in this case and so do packet socket. > Consider for example udp_recvmsg: it > never seems to return any error except -EAGAIN. > > Is this a bug? Man page for recvmsg says: > EFAULT The receive buffer pointer(s) point outside the process's address > space. > > this isn't very clear: does this mean "all pointers are invalid" > or "some pointers are invalid"? > Also, what if pointers themselves are valid but length > makes us go outside the address space? > > I'm guessing the simplest way is to clarify in the man page that > passing invalid pointers / lengths is not guaranteed > to result in EFAULT and that Linux makes no guarantees > about the returned length in this case. > > Cc linux-man in case they can suggest some insights on this. > >> If you perform some of the copy successfully, you have to report that >> length rather than just an error. >> >> Otherwise userland has no way to determine how much of the data was >> successfully sourced. >> >> I'm not applying this, sorry. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
