diff options
| author | Linus Lüssing | 2015-08-13 05:54:07 +0200 |
|---|---|---|
| committer | David S. Miller | 2015-08-13 17:08:39 -0700 |
| commit | a516993f0ac1694673412eb2d16a091eafa77d2a (patch) | |
| tree | 43e65ff360cc79cff96dc8c44f161fb0ad41b9c9 /net/bridge | |
| parent | 5b3e2e14eaa2a98232a4f292341fb88438685734 (diff) | |
net: fix wrong skb_get() usage / crash in IGMP/MLD parsing code
The recent refactoring of the IGMP and MLD parsing code into
ipv6_mc_check_mld() / ip_mc_check_igmp() introduced a potential crash /
BUG() invocation for bridges:
I wrongly assumed that skb_get() could be used as a simple reference
counter for an skb which is not the case. skb_get() bears additional
semantics, a user count. This leads to a BUG() invocation in
pskb_expand_head() / kernel panic if pskb_may_pull() is called on an skb
with a user count greater than one - unfortunately the refactoring did
just that.
Fixing this by removing the skb_get() call and changing the API: The
caller of ipv6_mc_check_mld() / ip_mc_check_igmp() now needs to
additionally check whether the returned skb_trimmed is a clone.
Fixes: 9afd85c9e455 ("net: Export IGMP/MLD message validation code")
Reported-by: Brenden Blanco <bblanco@plumgrid.com>
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/bridge')
| -rw-r--r-- | net/bridge/br_multicast.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c index 0b39dcc65b94..1285eaf5dc22 100644 --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -1591,7 +1591,7 @@ static int br_multicast_ipv4_rcv(struct net_bridge *br, break; } - if (skb_trimmed) + if (skb_trimmed && skb_trimmed != skb) kfree_skb(skb_trimmed); return err; @@ -1636,7 +1636,7 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br, break; } - if (skb_trimmed) + if (skb_trimmed && skb_trimmed != skb) kfree_skb(skb_trimmed); return err; |