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udp: fix jump label misuse 

The commit 60fb9567bf ("udp: implement complete book-keeping for
encap_needed") introduced a severe misuse of jump label APIs, which
syzbot, as reported by Eric, was able to exploit.

When multiple sockets/process can concurrently request (and than
disable) the udp encap, we need to track the activation counter with
*_inc()/*_dec() jump label variants, or we can experience bad things
at disable time.

Fixes: 60fb9567bf ("udp: implement complete book-keeping for encap_needed")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2018-11-15 02:34:50 +01:00 committed by David S. Miller
parent 37342bdaf5
commit 9c48060141
2 changed files with 4 additions and 4 deletions
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4
net/ipv4/udp.c
View File

@ -587,7 +587,7 @@ static inline bool __udp_is_mcast_sock(struct net *net, struct sock *sk,
DEFINE_STATIC_KEY_FALSE(udp_encap_needed_key);
void udp_encap_enable(void)
{
static_branch_enable(&udp_encap_needed_key);
static_branch_inc(&udp_encap_needed_key);
}
EXPORT_SYMBOL(udp_encap_enable);
@ -2524,7 +2524,7 @@ void udp_destroy_sock(struct sock *sk)
encap_destroy(sk);
}
if (up->encap_enabled)
static_branch_disable(&udp_encap_needed_key);
static_branch_dec(&udp_encap_needed_key);
}
}

4
net/ipv6/udp.c
View File

@ -448,7 +448,7 @@ csum_copy_err:
DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
void udpv6_encap_enable(void)
{
static_branch_enable(&udpv6_encap_needed_key);
static_branch_inc(&udpv6_encap_needed_key);
}
EXPORT_SYMBOL(udpv6_encap_enable);
@ -1579,7 +1579,7 @@ void udpv6_destroy_sock(struct sock *sk)
encap_destroy(sk);
}
if (up->encap_enabled)
static_branch_disable(&udpv6_encap_needed_key);
static_branch_dec(&udpv6_encap_needed_key);
}
inet6_destroy_sock(sk);