From: David Carlier <devnexen@gmail.com> stable inclusion from stable-v6.12.88 commit 0e550caa4bf575a06417de1e2b03a25f2caf88b6 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/15772 CVE: CVE-2026-53070 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 5638504a2aa9e1b9d72af9060df1a160cce2d379 ] gtp_genl_send_echo_req() runs as a generic netlink doit handler in process context with BH not disabled. It calls udp_tunnel_xmit_skb(), which eventually invokes iptunnel_xmit() — that uses __this_cpu_inc/dec on softnet_data.xmit.recursion to track the tunnel xmit recursion level. Without local_bh_disable(), the task may migrate between dev_xmit_recursion_inc() and dev_xmit_recursion_dec(), breaking the per-CPU counter pairing. The result is stale or negative recursion levels that can later produce false-positive SKB_DROP_REASON_RECURSION_LIMIT drops on either CPU. The other udp_tunnel_xmit_skb() call sites in gtp.c are unaffected: the data path runs under ndo_start_xmit and the echo response handlers run from the UDP encap rx softirq, both with BH already disabled. Fix it by disabling BH around the udp_tunnel_xmit_skb() call, mirroring commit 2cd7e6971fc2 ("sctp: disable BH before calling udp_tunnel_xmit_skb()"). Fixes: 6f1a9140ecda ("net: add xmit recursion limit to tunnel xmit functions") Cc: stable@vger.kernel.org Signed-off-by: David Carlier <devnexen@gmail.com> Link: https://patch.msgid.link/20260417055408.4667-1-devnexen@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> [ Context ] Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Wupeng Ma <mawupeng1@huawei.com> --- drivers/net/gtp.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 3684044547dc6..c6fe44be47d9f 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -1809,6 +1809,7 @@ static int gtp_genl_send_echo_req(struct sk_buff *skb, struct genl_info *info) return -ENODEV; } + local_bh_disable(); udp_tunnel_xmit_skb(rt, sk, skb_to_send, fl4.saddr, fl4.daddr, fl4.flowi4_tos, @@ -1818,6 +1819,7 @@ static int gtp_genl_send_echo_req(struct sk_buff *skb, struct genl_info *info) !net_eq(sock_net(sk), dev_net(gtp->dev)), false); + local_bh_enable(); return 0; } -- 2.43.0