From d25088932227680988a6b794221e031a7232f137 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Tue, 20 Sep 2022 18:31:30 +0200 Subject: [PATCH] netfilter: nf_ct_ftp: fix deadlock when nat rewrite is needed 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: c783a29c7e59 ("netfilter: nf_ct_ftp: prefer skb_linearize") Reported-by: Bruno de Paula Larini Signed-off-by: Florian Westphal --- net/netfilter/nf_conntrack_ftp.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_conntrack_ftp.c b/net/netfilter/nf_conntrack_ftp.c index 0d9332e9cf71..617f744a2e3a 100644 --- a/net/netfilter/nf_conntrack_ftp.c +++ b/net/netfilter/nf_conntrack_ftp.c @@ -33,6 +33,7 @@ MODULE_AUTHOR("Rusty Russell "); 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 @@ out_update_nl: 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; } -- 2.34.1