From: David Herrmann <dh.herrm...@gmail.com> Date: Wed, 21 Oct 2015 11:47:43 +0200
> Currently, NETLINK_LIST_MEMBERSHIPS grabs the netlink table while copying > the membership state to user-space. However, grabing the netlink table is > effectively a write_lock_irq(), and as such we should not be triggering > page-faults in the critical section. > > This can be easily reproduced by the following snippet: > int s = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE); > void *p = mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, > 0); > int r = getsockopt(s, 0x10e, 9, p, (void*)((char*)p + 4092)); > > This should work just fine, but currently triggers EFAULT and a possible > WARN_ON below handle_mm_fault(). > > Fix this by reducing locking of NETLINK_LIST_MEMBERSHIPS to a read-side > lock. The write-lock was overkill in the first place, and the read-lock > allows page-faults just fine. > > Reported-by: Dmitry Vyukov <dvyu...@google.com> > Signed-off-by: David Herrmann <dh.herrm...@gmail.com> Applied and queued up for -stable, thanks. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
