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netfilter: synproxy: protect nf_ct_seqadj_init() with conntrack lock

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nf_ct_seqadj_init() is called without holding the ct lock. This can race
with nf_ct_seq_adjust() when a connection is in CLOSE state due to an
RST or connection reopening. In addition for SYN_RECV state, concurrent
processing of packets can trigger nf_ct_seq_adjust() too. These
situations create a read/write data race.

As synproxy is the only user of nf_ct_seqadj_init() at the moment, fix
this by holding ct->lock inside nf_ct_seqadj_init() until all is done.

Fixes: 48b1de4c11 ("netfilter: add SYNPROXY core/target")
Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Fernando Fernandez Mancera 2026-05-26 23:58:30 +02:00 committed by Pablo Neira Ayuso
parent 992c20bc8a
commit 9e37388b80
1 changed files with 2 additions and 0 deletions
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2
net/netfilter/nf_conntrack_seqadj.c
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@ -17,12 +17,14 @@ int nf_ct_seqadj_init(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
if (off == 0)
return 0;
spin_lock_bh(&ct->lock);
set_bit(IPS_SEQ_ADJUST_BIT, &ct->status);
seqadj = nfct_seqadj(ct);
this_way = &seqadj->seq[dir];
this_way->offset_before = off;
this_way->offset_after = off;
spin_unlock_bh(&ct->lock);
return 0;
}
EXPORT_SYMBOL_GPL(nf_ct_seqadj_init);