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netfilter: nf_ct_ftp: fix deadlock when nat rewrite is needed

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We can't use ct->lock, this is already used by the seqadj internals.
When using ftp helper + nat, seqadj will attempt to acquire ct->lock
again.

Revert back to a global lock for now.

Fixes: c783a29c7e ("netfilter: nf_ct_ftp: prefer skb_linearize")
Reported-by: Bruno de Paula Larini <bruno.larini@riosoft.com.br>
Signed-off-by: Florian Westphal <fw@strlen.de>
This commit is contained in:
Florian Westphal 2022-09-20 18:31:30 +02:00
parent 62ce44c4ff
commit d250889322
1 changed files with 4 additions and 2 deletions
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6
net/netfilter/nf_conntrack_ftp.c
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@ -33,6 +33,7 @@ MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
MODULE_DESCRIPTION("ftp connection tracking helper");
MODULE_ALIAS("ip_conntrack_ftp");
MODULE_ALIAS_NFCT_HELPER(HELPER_NAME);
static DEFINE_SPINLOCK(nf_ftp_lock);
#define MAX_PORTS 8
static u_int16_t ports[MAX_PORTS];
@ -409,7 +410,8 @@ static int help(struct sk_buff *skb,
}
datalen = skb->len - dataoff;
spin_lock_bh(&ct->lock);
/* seqadj (nat) uses ct->lock internally, nf_nat_ftp would cause deadlock */
spin_lock_bh(&nf_ftp_lock);
fb_ptr = skb->data + dataoff;
ends_in_nl = (fb_ptr[datalen - 1] == '\n');
@ -538,7 +540,7 @@ static int help(struct sk_buff *skb,
if (ends_in_nl)
update_nl_seq(ct, seq, ct_ftp_info, dir, skb);
out:
spin_unlock_bh(&ct->lock);
spin_unlock_bh(&nf_ftp_lock);
return ret;
}