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mld: respect RCU rules in ip6_mc_source() and ip6_mc_msfilter()

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Whenever RCU protected list replaces an object,
the pointer to the new object needs to be updated
_before_ the call to kfree_rcu() or call_rcu()

Also ip6_mc_msfilter() needs to update the pointer
before releasing the mc_lock mutex.

Note that linux-5.13 was supporting kfree_rcu(NULL, rcu),
so this fix does not need the conditional test I was
forced to use in the equivalent patch for IPv4.

Fixes: 882ba1f73c ("mld: convert ipv6_mc_socklist->sflist to RCU")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2022-04-29 09:20:36 -07:00 committed by David S. Miller
parent dba5bdd57b
commit a9384a4c1d
1 changed files with 4 additions and 4 deletions
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8
net/ipv6/mcast.c
View File

@ -460,10 +460,10 @@ int ip6_mc_source(int add, int omode, struct sock *sk,
newpsl->sl_addr[i] = psl->sl_addr[i];
atomic_sub(struct_size(psl, sl_addr, psl->sl_max),
&sk->sk_omem_alloc);
kfree_rcu(psl, rcu);
}
rcu_assign_pointer(pmc->sflist, newpsl);
kfree_rcu(psl, rcu);
psl = newpsl;
rcu_assign_pointer(pmc->sflist, psl);
}
rv = 1; /* > 0 for insert logic below if sl_count is 0 */
for (i = 0; i < psl->sl_count; i++) {
@ -565,12 +565,12 @@ int ip6_mc_msfilter(struct sock *sk, struct group_filter *gsf,
psl->sl_count, psl->sl_addr, 0);
atomic_sub(struct_size(psl, sl_addr, psl->sl_max),
&sk->sk_omem_alloc);
kfree_rcu(psl, rcu);
} else {
ip6_mc_del_src(idev, group, pmc->sfmode, 0, NULL, 0);
}
mutex_unlock(&idev->mc_lock);
rcu_assign_pointer(pmc->sflist, newpsl);
mutex_unlock(&idev->mc_lock);
kfree_rcu(psl, rcu);
pmc->sfmode = gsf->gf_fmode;
err = 0;
done: