On Thu, May 28, 2015 at 06:15:11AM -0400, Neil Horman wrote: > On Wed, May 27, 2015 at 09:52:17PM -0300, mleitner@xxxxxxxxxx wrote: > > From: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> > > > > ->auto_asconf_splist is per namespace and mangled by functions like > > sctp_setsockopt_auto_asconf() which doesn't guarantee any serialization. > > > > Also, the call to inet_sk_copy_descendant() was backuping > > ->auto_asconf_list through the copy but was not honoring > > ->do_auto_asconf, which could lead to list corruption if it was > > different between both sockets. > > > > This commit thus fixes the list handling by adding a spinlock to protect > > against multiple writers and converts the list to be protected by RCU > > too, so that we don't have a lock inverstion issue at > > sctp_addr_wq_timeout_handler(). > > > > And as this list now uses RCU, we cannot do such backup and restore > > while copying descendant data anymore as readers may be traversing the > > list meanwhile. We fix this by simply ignoring/not copying those fields, > > placed at the end of struct sctp_sock, so we can just ignore it together > > with struct ipv6_pinfo data. For that we create sctp_copy_descendant() > > so we don't clutter inet_sk_copy_descendant() with SCTP info. > > > > Issue was found with a test application that kept flipping sysctl > > default_auto_asconf on and off. > > > > Fixes: 9f7d653b67ae ("sctp: Add Auto-ASCONF support (core).") > > Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> > > --- > > include/net/netns/sctp.h | 6 +++++- > > include/net/sctp/structs.h | 2 ++ > > net/sctp/protocol.c | 6 +++++- > > net/sctp/socket.c | 39 ++++++++++++++++++++++++++------------- > > 4 files changed, 38 insertions(+), 15 deletions(-) > > > > diff --git a/include/net/netns/sctp.h b/include/net/netns/sctp.h > > index 3573a81815ad9e0efb6ceb721eb066d3726419f0..e080bebb3147af39c8275261f57018eb01e917b0 100644 > > --- a/include/net/netns/sctp.h > > +++ b/include/net/netns/sctp.h > > @@ -30,12 +30,15 @@ struct netns_sctp { > > struct list_head local_addr_list; > > struct list_head addr_waitq; > > struct timer_list addr_wq_timer; > > - struct list_head auto_asconf_splist; > > + struct list_head __rcu auto_asconf_splist; > You should use the addr_wq_lock here instead of creating a new lock, as thats > already used to protect most accesses to the list you are concerned about. Ok, that works too. > Though truthfully, that shouldn't be necessecary. The list in question is only > read in one location and only written in one location. You can likely just > rcu-ify, as the write side is in process context and protected by lock_sock. It should, it's not protected by lock_sock as this list resides in netns_sctp structure, which lock_sock doesn't cover. Write side is in process context yes, but this list is written in sctp_init_sock(), sctp_destroy_sock() and sctp_setsockopt_auto_asconf(), so one could trigger this by either creating/destroying sockets if default_auto_asconf=1 or just by creating a bunch of sockets and flipping asconf via setsockopt (or a combination of these operations). (I'll point this out in the changelog) Btw I have two nits on the patch kindly broght to my attention already, on adding blank newline and bad comment block, will fix it in v2. Marcelo -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html