| Message ID | 20130702215015.GA1979@breakpoint.cc |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
On Tue, 2013-07-02 at 23:50 +0200, Sebastian Andrzej Siewior wrote: > Since commit c05cdb1b ("netlink: allow large data transfers from > user-space") the large skbs are allocated via vmalloc(). Trinity > triggered this in response: > > | BUG: unable to handle kernel paging request at ffffc900001bf001 > | IP: [<ffffffff8135270a>] skb_clone+0x1a/0xa0 > | Call Trace: > | [<ffffffff813cb107>] nl_fib_input+0x37/0x230 > | [<ffffffff8142c9b2>] ? _raw_read_unlock+0x22/0x40 > | [<ffffffff81380b1a>] netlink_unicast+0x13a/0x1f0 > | [<ffffffff81380ef7>] netlink_sendmsg+0x327/0x420 > > The problem is that the vmalloc() based skb ends exactly at size (where > ->end is pointing) and skb_shinfo() starts past ->end where we have our > guard page and hence we BUG(). > The question is should we fix this or forbid the skb_clone(). Fixing this > behaviour is tricky because even after we add space for struct > skb_shared_info we release the memory from the destructor so once the > first skbs is gone, the memory in the clone is invalid. > The other case where skb_clone() is used is when we have mutltiple > destinations. > Since I assume the initial target was to extend the size for > NETLINK_NETFILTER this patch limits to this target only and with single > destination. > Is this okay? > > Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> > --- > net/netlink/af_netlink.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c > index 68c1673..9926453 100644 > --- a/net/netlink/af_netlink.c > +++ b/net/netlink/af_netlink.c > @@ -2129,7 +2129,11 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock, > if (len > sk->sk_sndbuf - 32) > goto out; > err = -ENOBUFS; > - skb = netlink_alloc_large_skb(len); > + if (netlink_is_kernel(sk) && sk->sk_protocol == NETLINK_NETFILTER && > + !dst_group) > + skb = netlink_alloc_large_skb(len); > + else > + skb = alloc_skb(len, GFP_KERNEL); > if (skb == NULL) > goto out; > I believe you came too late, this was hopefully fixed here after some discussion last week : http://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=3a36515f729458c8efa0c124c7262d5843ad5c37 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jul 02, 2013 at 11:50:15PM +0200, Sebastian Andrzej Siewior wrote: > Since commit c05cdb1b ("netlink: allow large data transfers from > user-space") the large skbs are allocated via vmalloc(). Trinity > triggered this in response: > > | BUG: unable to handle kernel paging request at ffffc900001bf001 > | IP: [<ffffffff8135270a>] skb_clone+0x1a/0xa0 > | Call Trace: > | [<ffffffff813cb107>] nl_fib_input+0x37/0x230 > | [<ffffffff8142c9b2>] ? _raw_read_unlock+0x22/0x40 > | [<ffffffff81380b1a>] netlink_unicast+0x13a/0x1f0 > | [<ffffffff81380ef7>] netlink_sendmsg+0x327/0x420 > > The problem is that the vmalloc() based skb ends exactly at size (where > ->end is pointing) and skb_shinfo() starts past ->end where we have our > guard page and hence we BUG(). > The question is should we fix this or forbid the skb_clone(). Fixing this > behaviour is tricky because even after we add space for struct > skb_shared_info we release the memory from the destructor so once the > first skbs is gone, the memory in the clone is invalid. > The other case where skb_clone() is used is when we have mutltiple > destinations. > Since I assume the initial target was to extend the size for > NETLINK_NETFILTER this patch limits to this target only and with single > destination. > Is this okay? Did you notice this patch? 3a36515 netlink: fix splat in skb_clone with large messages Regards. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jul 02, 2013 at 03:07:14PM -0700, Eric Dumazet wrote: > I believe you came too late, this was hopefully fixed here after some > discussion last week : Oh not again. Okay so this is gone. Sebastian -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 68c1673..9926453 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2129,7 +2129,11 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct socket *sock, if (len > sk->sk_sndbuf - 32) goto out; err = -ENOBUFS; - skb = netlink_alloc_large_skb(len); + if (netlink_is_kernel(sk) && sk->sk_protocol == NETLINK_NETFILTER && + !dst_group) + skb = netlink_alloc_large_skb(len); + else + skb = alloc_skb(len, GFP_KERNEL); if (skb == NULL) goto out;
Since commit c05cdb1b ("netlink: allow large data transfers from user-space") the large skbs are allocated via vmalloc(). Trinity triggered this in response: | BUG: unable to handle kernel paging request at ffffc900001bf001 | IP: [<ffffffff8135270a>] skb_clone+0x1a/0xa0 | Call Trace: | [<ffffffff813cb107>] nl_fib_input+0x37/0x230 | [<ffffffff8142c9b2>] ? _raw_read_unlock+0x22/0x40 | [<ffffffff81380b1a>] netlink_unicast+0x13a/0x1f0 | [<ffffffff81380ef7>] netlink_sendmsg+0x327/0x420 The problem is that the vmalloc() based skb ends exactly at size (where ->end is pointing) and skb_shinfo() starts past ->end where we have our guard page and hence we BUG(). The question is should we fix this or forbid the skb_clone(). Fixing this behaviour is tricky because even after we add space for struct skb_shared_info we release the memory from the destructor so once the first skbs is gone, the memory in the clone is invalid. The other case where skb_clone() is used is when we have mutltiple destinations. Since I assume the initial target was to extend the size for NETLINK_NETFILTER this patch limits to this target only and with single destination. Is this okay? Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc> --- net/netlink/af_netlink.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)