diff mbox series

[net,5/5] netfilter: nf_ct_ftp: fix deadlock when nat rewrite is needed

Message ID 20220921073825.4658-6-fw@strlen.de (mailing list archive)
State Accepted
Commit d25088932227680988a6b794221e031a7232f137
Delegated to: Netdev Maintainers
Headers show
Series [net,1/5] netfilter: conntrack: remove nf_conntrack_helper documentation | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/subject_prefix success Link
netdev/cover_letter success Pull request is its own cover letter
netdev/patch_count success Link
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1 this patch: 1
netdev/cc_maintainers fail 1 blamed authors not CCed: pablo@netfilter.org; 3 maintainers not CCed: pablo@netfilter.org coreteam@netfilter.org kadlec@netfilter.org
netdev/build_clang success Errors and warnings before: 0 this patch: 0
netdev/module_param success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 1 this patch: 1
netdev/checkpatch warning WARNING: line length of 84 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Florian Westphal Sept. 21, 2022, 7:38 a.m. UTC
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 <bruno.larini@riosoft.com.br>
Signed-off-by: Florian Westphal <fw@strlen.de>
---
 net/netfilter/nf_conntrack_ftp.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

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 <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;
 }