[PATCH net 0/2] Netfilter/IPVS fixes for net

[PATCH net 0/2] Netfilter/IPVS fixes for net

[Pablo Neira Ayuso]

Hi,

The following patchset contain Netfilter/IPVS fixes for net:

1) Fix KMSAN uninit-value in do_output_route4, reported by syzbot.
   Patch from Julian Anastasov.

2) ipset hashtable set type breaks up the hashtable into regions of
   2^10 buckets. Fix the macro that determines the hashtable lock
   region to protect concurrent updates. From Jozsef Kadlecsik.

Please, pull these changes from:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git nf-25-05-08

Thanks.

----------------------------------------------------------------

The following changes since commit 9540984da649d46f699c47f28c68bbd3c9d99e4c:

  Merge tag 'wireless-2025-05-06' of https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless (2025-05-06 19:06:50 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf.git tags/nf-25-05-08

for you to fetch changes up to 8478a729c0462273188263136880480729e9efca:

  netfilter: ipset: fix region locking in hash types (2025-05-07 23:57:31 +0200)

----------------------------------------------------------------
netfilter pull request 25-05-08

----------------------------------------------------------------
Jozsef Kadlecsik (1):
      netfilter: ipset: fix region locking in hash types

Julian Anastasov (1):
      ipvs: fix uninit-value for saddr in do_output_route4

 net/netfilter/ipset/ip_set_hash_gen.h |  2 +-
 net/netfilter/ipvs/ip_vs_xmit.c       | 27 ++++++++-------------------
 2 files changed, 9 insertions(+), 20 deletions(-)

[PATCH net 1/2] ipvs: fix uninit-value for saddr in do_output_route4

[Pablo Neira Ayuso]

From: Julian Anastasov <ja@ssi.bg>

syzbot reports for uninit-value for the saddr argument [1].
commit 4754957f04f5 ("ipvs: do not use random local source address for
tunnels") already implies that the input value of saddr
should be ignored but the code is still reading it which can prevent
to connect the route. Fix it by changing the argument to ret_saddr.

[1]
BUG: KMSAN: uninit-value in do_output_route4+0x42c/0x4d0 net/netfilter/ipvs/ip_vs_xmit.c:147
 do_output_route4+0x42c/0x4d0 net/netfilter/ipvs/ip_vs_xmit.c:147
 __ip_vs_get_out_rt+0x403/0x21d0 net/netfilter/ipvs/ip_vs_xmit.c:330
 ip_vs_tunnel_xmit+0x205/0x2380 net/netfilter/ipvs/ip_vs_xmit.c:1136
 ip_vs_in_hook+0x1aa5/0x35b0 net/netfilter/ipvs/ip_vs_core.c:2063
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_slow+0xf7/0x400 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:269 [inline]
 __ip_local_out+0x758/0x7e0 net/ipv4/ip_output.c:118
 ip_local_out net/ipv4/ip_output.c:127 [inline]
 ip_send_skb+0x6a/0x3c0 net/ipv4/ip_output.c:1501
 udp_send_skb+0xfda/0x1b70 net/ipv4/udp.c:1195
 udp_sendmsg+0x2fe3/0x33c0 net/ipv4/udp.c:1483
 inet_sendmsg+0x1fc/0x280 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x267/0x380 net/socket.c:727
 ____sys_sendmsg+0x91b/0xda0 net/socket.c:2566
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2620
 __sys_sendmmsg+0x41d/0x880 net/socket.c:2702
 __compat_sys_sendmmsg net/compat.c:360 [inline]
 __do_compat_sys_sendmmsg net/compat.c:367 [inline]
 __se_compat_sys_sendmmsg net/compat.c:364 [inline]
 __ia32_compat_sys_sendmmsg+0xc8/0x140 net/compat.c:364
 ia32_sys_call+0x3ffa/0x41f0 arch/x86/include/generated/asm/syscalls_32.h:346
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x110 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4167 [inline]
 slab_alloc_node mm/slub.c:4210 [inline]
 __kmalloc_cache_noprof+0x8fa/0xe00 mm/slub.c:4367
 kmalloc_noprof include/linux/slab.h:905 [inline]
 ip_vs_dest_dst_alloc net/netfilter/ipvs/ip_vs_xmit.c:61 [inline]
 __ip_vs_get_out_rt+0x35d/0x21d0 net/netfilter/ipvs/ip_vs_xmit.c:323
 ip_vs_tunnel_xmit+0x205/0x2380 net/netfilter/ipvs/ip_vs_xmit.c:1136
 ip_vs_in_hook+0x1aa5/0x35b0 net/netfilter/ipvs/ip_vs_core.c:2063
 nf_hook_entry_hookfn include/linux/netfilter.h:154 [inline]
 nf_hook_slow+0xf7/0x400 net/netfilter/core.c:626
 nf_hook include/linux/netfilter.h:269 [inline]
 __ip_local_out+0x758/0x7e0 net/ipv4/ip_output.c:118
 ip_local_out net/ipv4/ip_output.c:127 [inline]
 ip_send_skb+0x6a/0x3c0 net/ipv4/ip_output.c:1501
 udp_send_skb+0xfda/0x1b70 net/ipv4/udp.c:1195
 udp_sendmsg+0x2fe3/0x33c0 net/ipv4/udp.c:1483
 inet_sendmsg+0x1fc/0x280 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x267/0x380 net/socket.c:727
 ____sys_sendmsg+0x91b/0xda0 net/socket.c:2566
 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2620
 __sys_sendmmsg+0x41d/0x880 net/socket.c:2702
 __compat_sys_sendmmsg net/compat.c:360 [inline]
 __do_compat_sys_sendmmsg net/compat.c:367 [inline]
 __se_compat_sys_sendmmsg net/compat.c:364 [inline]
 __ia32_compat_sys_sendmmsg+0xc8/0x140 net/compat.c:364
 ia32_sys_call+0x3ffa/0x41f0 arch/x86/include/generated/asm/syscalls_32.h:346
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xb0/0x110 arch/x86/entry/syscall_32.c:306
 do_fast_syscall_32+0x38/0x80 arch/x86/entry/syscall_32.c:331
 do_SYSENTER_32+0x1f/0x30 arch/x86/entry/syscall_32.c:369
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e

CPU: 0 UID: 0 PID: 22408 Comm: syz.4.5165 Not tainted 6.15.0-rc3-syzkaller-00019-gbc3372351d0c #0 PREEMPT(undef)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025

Reported-by: syzbot+04b9a82855c8aed20860@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/68138dfa.050a0220.14dd7d.0017.GAE@google.com/
Fixes: 4754957f04f5 ("ipvs: do not use random local source address for tunnels")
Signed-off-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Simon Horman <horms@kernel.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/ipvs/ip_vs_xmit.c | 27 ++++++++-------------------
 1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 3313bceb6cc9..014f07740369 100644
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -119,13 +119,12 @@ __mtu_check_toobig_v6(const struct sk_buff *skb, u32 mtu)
 	return false;
 }
 
-/* Get route to daddr, update *saddr, optionally bind route to saddr */
+/* Get route to daddr, optionally bind route to saddr */
 static struct rtable *do_output_route4(struct net *net, __be32 daddr,
-				       int rt_mode, __be32 *saddr)
+				       int rt_mode, __be32 *ret_saddr)
 {
 	struct flowi4 fl4;
 	struct rtable *rt;
-	bool loop = false;
 
 	memset(&fl4, 0, sizeof(fl4));
 	fl4.daddr = daddr;
@@ -135,23 +134,17 @@ static struct rtable *do_output_route4(struct net *net, __be32 daddr,
 retry:
 	rt = ip_route_output_key(net, &fl4);
 	if (IS_ERR(rt)) {
-		/* Invalid saddr ? */
-		if (PTR_ERR(rt) == -EINVAL && *saddr &&
-		    rt_mode & IP_VS_RT_MODE_CONNECT && !loop) {
-			*saddr = 0;
-			flowi4_update_output(&fl4, 0, daddr, 0);
-			goto retry;
-		}
 		IP_VS_DBG_RL("ip_route_output error, dest: %pI4\n", &daddr);
 		return NULL;
-	} else if (!*saddr && rt_mode & IP_VS_RT_MODE_CONNECT && fl4.saddr) {
+	}
+	if (rt_mode & IP_VS_RT_MODE_CONNECT && fl4.saddr) {
 		ip_rt_put(rt);
-		*saddr = fl4.saddr;
 		flowi4_update_output(&fl4, 0, daddr, fl4.saddr);
-		loop = true;
+		rt_mode = 0;
 		goto retry;
 	}
-	*saddr = fl4.saddr;
+	if (ret_saddr)
+		*ret_saddr = fl4.saddr;
 	return rt;
 }
 
@@ -344,19 +337,15 @@ __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
 		if (ret_saddr)
 			*ret_saddr = dest_dst->dst_saddr.ip;
 	} else {
-		__be32 saddr = htonl(INADDR_ANY);
-
 		noref = 0;
 
 		/* For such unconfigured boxes avoid many route lookups
 		 * for performance reasons because we do not remember saddr
 		 */
 		rt_mode &= ~IP_VS_RT_MODE_CONNECT;
-		rt = do_output_route4(net, daddr, rt_mode, &saddr);
+		rt = do_output_route4(net, daddr, rt_mode, ret_saddr);
 		if (!rt)
 			goto err_unreach;
-		if (ret_saddr)
-			*ret_saddr = saddr;
 	}
 
 	local = (rt->rt_flags & RTCF_LOCAL) ? 1 : 0;
-- 
2.30.2

[PATCH net 2/2] netfilter: ipset: fix region locking in hash types

[Pablo Neira Ayuso]

From: Jozsef Kadlecsik <kadlec@netfilter.org>

Region locking introduced in v5.6-rc4 contained three macros to handle
the region locks: ahash_bucket_start(), ahash_bucket_end() which gave
back the start and end hash bucket values belonging to a given region
lock and ahash_region() which should give back the region lock belonging
to a given hash bucket. The latter was incorrect which can lead to a
race condition between the garbage collector and adding new elements
when a hash type of set is defined with timeouts.

Fixes: f66ee0410b1c ("netfilter: ipset: Fix "INFO: rcu detected stall in hash_xxx" reports")
Reported-by: Kota Toda <kota.toda@gmo-cybersecurity.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/ipset/ip_set_hash_gen.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index cf3ce72c3de6..5251524b96af 100644
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -64,7 +64,7 @@ struct hbucket {
 #define ahash_sizeof_regions(htable_bits)		\
 	(ahash_numof_locks(htable_bits) * sizeof(struct ip_set_region))
 #define ahash_region(n, htable_bits)		\
-	((n) % ahash_numof_locks(htable_bits))
+	((n) / jhash_size(HTABLE_REGION_BITS))
 #define ahash_bucket_start(h,  htable_bits)	\
 	((htable_bits) < HTABLE_REGION_BITS ? 0	\
 		: (h) * jhash_size(HTABLE_REGION_BITS))
-- 
2.30.2

Re: [PATCH net 1/2] ipvs: fix uninit-value for saddr in do_output_route4

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (main)
by Pablo Neira Ayuso <pablo@netfilter.org>:

On Thu,  8 May 2025 00:19:51 +0200 you wrote:
> From: Julian Anastasov <ja@ssi.bg>
> 
> syzbot reports for uninit-value for the saddr argument [1].
> commit 4754957f04f5 ("ipvs: do not use random local source address for
> tunnels") already implies that the input value of saddr
> should be ignored but the code is still reading it which can prevent
> to connect the route. Fix it by changing the argument to ret_saddr.
> 
> [...]

Here is the summary with links:
  - [net,1/2] ipvs: fix uninit-value for saddr in do_output_route4
    https://git.kernel.org/netdev/net/c/e34090d7214e
  - [net,2/2] netfilter: ipset: fix region locking in hash types
    https://git.kernel.org/netdev/net/c/8478a729c046

You are awesome, thank you!
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