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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , coreteam@netfilter.org (open list:NETFILTER), netdev@vger.kernel.org (open list:NETWORKING [GENERAL]), linux-kernel@vger.kernel.org (open list) Subject: [PATCH] netfilter: synproxy: fix unaligned access to TCP timestamp option Date: Sun, 7 Jun 2026 09:44:47 -0700 Message-ID: <20260607164447.39700-1-rosenp@gmail.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable synproxy_tstamp_adjust() reads and writes the TSval and TSecr fields of the TCP Timestamp option via direct __be32 pointer dereferences. These fields are at byte offsets 2 and 6 within the option, which are only 2-byte aligned =E2=80=94 not 4-byte aligned for __be32 access. Replace with get_unaligned_be32() / put_unaligned_be32() to safely handle the unaligned access on strict-alignment architectures. Assisted-by: opencode:big-pickle Signed-off-by: Rosen Penev --- net/netfilter/nf_synproxy_core.c | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-) diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_c= ore.c index ed00114f65f3..0a038b9b5169 100644 --- a/net/netfilter/nf_synproxy_core.c +++ b/net/netfilter/nf_synproxy_core.c @@ -191,7 +191,7 @@ synproxy_tstamp_adjust(struct sk_buff *skb, unsigned in= t protoff, const struct nf_conn_synproxy *synproxy) { unsigned int optoff, optend; - __be32 *ptr, old; + __be32 old; =20 if (synproxy->tsoff =3D=3D 0) return 1; @@ -221,18 +221,22 @@ synproxy_tstamp_adjust(struct sk_buff *skb, unsigned = int protoff, if (op[0] =3D=3D TCPOPT_TIMESTAMP && op[1] =3D=3D TCPOLEN_TIMESTAMP) { if (CTINFO2DIR(ctinfo) =3D=3D IP_CT_DIR_REPLY) { - ptr =3D (__be32 *)&op[2]; - old =3D *ptr; - *ptr =3D htonl(ntohl(*ptr) - - synproxy->tsoff); + u32 tsval =3D get_unaligned_be32(&op[2]); + u32 new_tsval =3D tsval - synproxy->tsoff; + + old =3D cpu_to_be32(tsval); + put_unaligned_be32(new_tsval, &op[2]); + inet_proto_csum_replace4(&th->check, skb, + old, cpu_to_be32(new_tsval), false); } else { - ptr =3D (__be32 *)&op[6]; - old =3D *ptr; - *ptr =3D htonl(ntohl(*ptr) + - synproxy->tsoff); + u32 tsecr =3D get_unaligned_be32(&op[6]); + u32 new_tsecr =3D tsecr + synproxy->tsoff; + + old =3D cpu_to_be32(tsecr); + put_unaligned_be32(new_tsecr, &op[6]); + inet_proto_csum_replace4(&th->check, skb, + old, cpu_to_be32(new_tsecr), false); } - inet_proto_csum_replace4(&th->check, skb, - old, *ptr, false); return 1; } optoff +=3D op[1]; --=20 2.54.0