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From: Fedor Pchelkin <pchelkin@ispras.ru>
To: Simon Horman <horms@verge.net.au>,
	Julian Anastasov <ja@ssi.bg>
Cc: Fedor Pchelkin <pchelkin@ispras.ru>,
	Pablo Neira Ayuso <pablo@netfilter.org>,
	Jozsef Kadlecsik <kadlec@netfilter.org>,
	Florian Westphal <fw@strlen.de>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>,
	Paolo Abeni <pabeni@redhat.com>,
	Dwip Banerjee <dwip@linux.vnet.ibm.com>,
	netdev@vger.kernel.org,
	lvs-devel@vger.kernel.org,
	netfilter-devel@vger.kernel.org,
	coreteam@netfilter.org,
	linux-kernel@vger.kernel.org,
	Alexey Khoroshilov <khoroshilov@ispras.ru>,
	lvc-project@linuxtesting.org
Subject: [PATCH net] net: ipvs: avoid stat macros calls from preemptible context
Date: Mon, 15 Jan 2024 17:39:22 +0300
Message-ID: <20240115143923.31243-1-pchelkin@ispras.ru>
Precedence: bulk
MIME-Version: 1.0
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Inside decrement_ttl() upon discovering that the packet ttl has exceeded,
__IP_INC_STATS and __IP6_INC_STATS macros can be called from preemptible
context having the following backtrace:

check_preemption_disabled: 48 callbacks suppressed
BUG: using __this_cpu_add() in preemptible [00000000] code: curl/1177
caller is decrement_ttl+0x217/0x830
CPU: 5 PID: 1177 Comm: curl Not tainted 6.7.0+ #34
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xbd/0xe0
 check_preemption_disabled+0xd1/0xe0
 decrement_ttl+0x217/0x830
 __ip_vs_get_out_rt+0x4e0/0x1ef0
 ip_vs_nat_xmit+0x205/0xcd0
 ip_vs_in_hook+0x9b1/0x26a0
 nf_hook_slow+0xc2/0x210
 nf_hook+0x1fb/0x770
 __ip_local_out+0x33b/0x640
 ip_local_out+0x2a/0x490
 __ip_queue_xmit+0x990/0x1d10
 __tcp_transmit_skb+0x288b/0x3d10
 tcp_connect+0x3466/0x5180
 tcp_v4_connect+0x1535/0x1bb0
 __inet_stream_connect+0x40d/0x1040
 inet_stream_connect+0x57/0xa0
 __sys_connect_file+0x162/0x1a0
 __sys_connect+0x137/0x160
 __x64_sys_connect+0x72/0xb0
 do_syscall_64+0x6f/0x140
 entry_SYSCALL_64_after_hwframe+0x6e/0x76
RIP: 0033:0x7fe6dbbc34e0

Use the corresponding preemption-aware variants: IP_INC_STATS and
IP6_INC_STATS.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 8d8e20e2d7bb ("ipvs: Decrement ttl")
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
---
 net/netfilter/ipvs/ip_vs_xmit.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 9193e109e6b3..65e0259178da 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -271,7 +271,7 @@ static inline bool decrement_ttl(struct netns_ipvs *ipvs,
 			skb->dev = dst->dev;
 			icmpv6_send(skb, ICMPV6_TIME_EXCEED,
 				    ICMPV6_EXC_HOPLIMIT, 0);
-			__IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
+			IP6_INC_STATS(net, idev, IPSTATS_MIB_INHDRERRORS);
 
 			return false;
 		}
@@ -286,7 +286,7 @@ static inline bool decrement_ttl(struct netns_ipvs *ipvs,
 	{
 		if (ip_hdr(skb)->ttl <= 1) {
 			/* Tell the sender its packet died... */
-			__IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
+			IP_INC_STATS(net, IPSTATS_MIB_INHDRERRORS);
 			icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0);
 			return false;
 		}
-- 
2.43.0