diff options
author | Daniel Borkmann <dborkman@redhat.com> | 2014-11-05 20:27:38 +0100 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2014-11-06 04:12:30 +0100 |
commit | 4c672e4b42bc8046d63a6eb0a2c6a450a501af32 (patch) | |
tree | a6f7f031f6c1995c8854775599919eb18fdfecc6 /net/ipv4/igmp.c | |
parent | net: Convert SEQ_START_TOKEN/seq_printf to seq_puts (diff) | |
download | linux-4c672e4b42bc8046d63a6eb0a2c6a450a501af32.tar.xz linux-4c672e4b42bc8046d63a6eb0a2c6a450a501af32.zip |
ipv6: mld: fix add_grhead skb_over_panic for devs with large MTUs
It has been reported that generating an MLD listener report on
devices with large MTUs (e.g. 9000) and a high number of IPv6
addresses can trigger a skb_over_panic():
skbuff: skb_over_panic: text:ffffffff80612a5d len:3776 put:20
head:ffff88046d751000 data:ffff88046d751010 tail:0xed0 end:0xec0
dev:port1
------------[ cut here ]------------
kernel BUG at net/core/skbuff.c:100!
invalid opcode: 0000 [#1] SMP
Modules linked in: ixgbe(O)
CPU: 3 PID: 0 Comm: swapper/3 Tainted: G O 3.14.23+ #4
[...]
Call Trace:
<IRQ>
[<ffffffff80578226>] ? skb_put+0x3a/0x3b
[<ffffffff80612a5d>] ? add_grhead+0x45/0x8e
[<ffffffff80612e3a>] ? add_grec+0x394/0x3d4
[<ffffffff80613222>] ? mld_ifc_timer_expire+0x195/0x20d
[<ffffffff8061308d>] ? mld_dad_timer_expire+0x45/0x45
[<ffffffff80255b5d>] ? call_timer_fn.isra.29+0x12/0x68
[<ffffffff80255d16>] ? run_timer_softirq+0x163/0x182
[<ffffffff80250e6f>] ? __do_softirq+0xe0/0x21d
[<ffffffff8025112b>] ? irq_exit+0x4e/0xd3
[<ffffffff802214bb>] ? smp_apic_timer_interrupt+0x3b/0x46
[<ffffffff8063f10a>] ? apic_timer_interrupt+0x6a/0x70
mld_newpack() skb allocations are usually requested with dev->mtu
in size, since commit 72e09ad107e7 ("ipv6: avoid high order allocations")
we have changed the limit in order to be less likely to fail.
However, in MLD/IGMP code, we have some rather ugly AVAILABLE(skb)
macros, which determine if we may end up doing an skb_put() for
adding another record. To avoid possible fragmentation, we check
the skb's tailroom as skb->dev->mtu - skb->len, which is a wrong
assumption as the actual max allocation size can be much smaller.
The IGMP case doesn't have this issue as commit 57e1ab6eaddc
("igmp: refine skb allocations") stores the allocation size in
the cb[].
Set a reserved_tailroom to make it fit into the MTU and use
skb_availroom() helper instead. This also allows to get rid of
igmp_skb_size().
Reported-by: Wei Liu <lw1a2.jing@gmail.com>
Fixes: 72e09ad107e7 ("ipv6: avoid high order allocations")
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: David L Stevens <david.stevens@oracle.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/igmp.c')
-rw-r--r-- | net/ipv4/igmp.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index 1e4adae2bde0..666cf364df86 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -318,9 +318,7 @@ igmp_scount(struct ip_mc_list *pmc, int type, int gdeleted, int sdeleted) return scount; } -#define igmp_skb_size(skb) (*(unsigned int *)((skb)->cb)) - -static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size) +static struct sk_buff *igmpv3_newpack(struct net_device *dev, unsigned int mtu) { struct sk_buff *skb; struct rtable *rt; @@ -330,6 +328,7 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size) struct flowi4 fl4; int hlen = LL_RESERVED_SPACE(dev); int tlen = dev->needed_tailroom; + unsigned int size = mtu; while (1) { skb = alloc_skb(size + hlen + tlen, @@ -341,7 +340,6 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size) return NULL; } skb->priority = TC_PRIO_CONTROL; - igmp_skb_size(skb) = size; rt = ip_route_output_ports(net, &fl4, NULL, IGMPV3_ALL_MCR, 0, 0, 0, @@ -354,6 +352,8 @@ static struct sk_buff *igmpv3_newpack(struct net_device *dev, int size) skb_dst_set(skb, &rt->dst); skb->dev = dev; + skb->reserved_tailroom = skb_end_offset(skb) - + min(mtu, skb_end_offset(skb)); skb_reserve(skb, hlen); skb_reset_network_header(skb); @@ -423,8 +423,7 @@ static struct sk_buff *add_grhead(struct sk_buff *skb, struct ip_mc_list *pmc, return skb; } -#define AVAILABLE(skb) ((skb) ? ((skb)->dev ? igmp_skb_size(skb) - (skb)->len : \ - skb_tailroom(skb)) : 0) +#define AVAILABLE(skb) ((skb) ? skb_availroom(skb) : 0) static struct sk_buff *add_grec(struct sk_buff *skb, struct ip_mc_list *pmc, int type, int gdeleted, int sdeleted) |