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authorDaniel Borkmann <dborkman@redhat.com>2014-11-05 20:27:38 +0100
committerDavid S. Miller <davem@davemloft.net>2014-11-05 22:12:30 -0500
commit4c672e4b42bc8046d63a6eb0a2c6a450a501af32 (patch)
treea6f7f031f6c1995c8854775599919eb18fdfecc6 /net/ipv4/igmp.c
parent1744bea1fa382f67263fdd9fee51d603fddb3da6 (diff)
downloadop-kernel-dev-4c672e4b42bc8046d63a6eb0a2c6a450a501af32.zip
op-kernel-dev-4c672e4b42bc8046d63a6eb0a2c6a450a501af32.tar.gz
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.c11
1 files changed, 5 insertions, 6 deletions
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 1e4adae..666cf36 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)
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