linux-stable.git/net/bridge/br_multicast.c, branch linux-rolling-stable Linux kernel stable tree bridge: mcast: Fix a possible use-after-free when removing a bridge port 2026-06-01T15:54:50+00:00 Ido Schimmel idosch@nvidia.com 2026-05-17T12:11:21+00:00 7213256c91ed778a0997c2029c152b18dc50e4fd [ Upstream commit 4df78ff02629c7729168f0696a7a2123c389818d ] When per-VLAN multicast snooping is enabled, the bridge iterates over all the bridge ports, disables the per-port multicast context on each port and enables the per-{port, VLAN} multicast contexts instead. The reverse happens when per-VLAN multicast snooping is disabled. When global multicast snooping is enabled, the bridge iterates over all the bridge ports and enables the per-port multicast context on each port. The reverse happens when multicast snooping is disabled. The above scheme can result in a situation where both types of contexts (per-port and per-{port, VLAN}) are enabled on a single bridge port: # ip link add name br1 up type bridge mcast_snooping 1 mcast_querier 1 vlan_filtering 1 # ip link add name dummy1 up master br1 type dummy # ip link set dev br1 type bridge mcast_vlan_snooping 1 # ip link set dev br1 type bridge mcast_snooping 0 # ip link set dev br1 type bridge mcast_snooping 1 This is not intended and it is a problem since the commit cited below. Prior to this commit, when removing a bridge port, br_multicast_disable_port() would disable the per-port multicast context and the per-{port, VLAN} multicast contexts would get disabled when flushing VLANs. After this commit, br_multicast_disable_port() only disables the per-port multicast context if per-VLAN multicast snooping is disabled. If both types of contexts were enabled on the port when it was removed, the per-port multicast context would remain enabled when freeing the bridge port, leading to a use-after-free [1]. Fix by preventing the bridge from enabling / disabling the per-port multicast contexts when toggling global multicast snooping if per-VLAN multicast snooping is enabled. [1] ODEBUG: free active (active state 0) object: ffff88810f8bda78 object type: timer_list hint: br_ip6_multicast_port_query_expired (net/bridge/br_multicast.c:1927) WARNING: lib/debugobjects.c:629 at debug_print_object+0x1b1/0x3e0, CPU#5: swapper/5/0 [...] Call Trace: <IRQ> __debug_check_no_obj_freed (lib/debugobjects.c:1116) kfree (mm/slub.c:2620 mm/slub.c:6250 mm/slub.c:6565) kobject_cleanup (lib/kobject.c:689) rcu_do_batch (kernel/rcu/tree.c:2617) rcu_core (kernel/rcu/tree.c:2869) handle_softirqs (kernel/softirq.c:622) __irq_exit_rcu (kernel/softirq.c:656 kernel/softirq.c:496 kernel/softirq.c:735) irq_exit_rcu (kernel/softirq.c:752) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1061 (discriminator 47) arch/x86/kernel/apic/apic.c:1061 (discriminator 47)) </IRQ> Fixes: 4b30ae9adb04 ("net: bridge: mcast: re-implement br_multicast_{enable, disable}_port functions") Reported-by: syzbot+ae231e0552fa77b26ea1@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/87qznowlfs.ffs@tglx/ Reported-by: Thomas Gleixner <tglx@kernel.org> Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com> Signed-off-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20260517121122.188333-2-idosch@nvidia.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 4df78ff02629c7729168f0696a7a2123c389818d ]

When per-VLAN multicast snooping is enabled, the bridge iterates over
all the bridge ports, disables the per-port multicast context on each
port and enables the per-{port, VLAN} multicast contexts instead. The
reverse happens when per-VLAN multicast snooping is disabled.

When global multicast snooping is enabled, the bridge iterates over all
the bridge ports and enables the per-port multicast context on each
port. The reverse happens when multicast snooping is disabled.

The above scheme can result in a situation where both types of contexts
(per-port and per-{port, VLAN}) are enabled on a single bridge port:

 # ip link add name br1 up type bridge mcast_snooping 1 mcast_querier 1 vlan_filtering 1
 # ip link add name dummy1 up master br1 type dummy
 # ip link set dev br1 type bridge mcast_vlan_snooping 1
 # ip link set dev br1 type bridge mcast_snooping 0
 # ip link set dev br1 type bridge mcast_snooping 1

This is not intended and it is a problem since the commit cited below.
Prior to this commit, when removing a bridge port,
br_multicast_disable_port() would disable the per-port multicast context
and the per-{port, VLAN} multicast contexts would get disabled when
flushing VLANs.

After this commit, br_multicast_disable_port() only disables the
per-port multicast context if per-VLAN multicast snooping is disabled.
If both types of contexts were enabled on the port when it was removed,
the per-port multicast context would remain enabled when freeing the
bridge port, leading to a use-after-free [1].

Fix by preventing the bridge from enabling / disabling the per-port
multicast contexts when toggling global multicast snooping if per-VLAN
multicast snooping is enabled.

[1]
ODEBUG: free active (active state 0) object: ffff88810f8bda78 object type: timer_list hint: br_ip6_multicast_port_query_expired (net/bridge/br_multicast.c:1927)
WARNING: lib/debugobjects.c:629 at debug_print_object+0x1b1/0x3e0, CPU#5: swapper/5/0
[...]
Call Trace:
<IRQ>
__debug_check_no_obj_freed (lib/debugobjects.c:1116)
kfree (mm/slub.c:2620 mm/slub.c:6250 mm/slub.c:6565)
kobject_cleanup (lib/kobject.c:689)
rcu_do_batch (kernel/rcu/tree.c:2617)
rcu_core (kernel/rcu/tree.c:2869)
handle_softirqs (kernel/softirq.c:622)
__irq_exit_rcu (kernel/softirq.c:656 kernel/softirq.c:496 kernel/softirq.c:735)
irq_exit_rcu (kernel/softirq.c:752)
sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1061 (discriminator 47) arch/x86/kernel/apic/apic.c:1061 (discriminator 47))
</IRQ>

Fixes: 4b30ae9adb04 ("net: bridge: mcast: re-implement br_multicast_{enable, disable}_port functions")
Reported-by: syzbot+ae231e0552fa77b26ea1@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/87qznowlfs.ffs@tglx/
Reported-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260517121122.188333-2-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
treewide: Replace kmalloc with kmalloc_obj for non-scalar types 2026-02-21T09:02:28+00:00 Kees Cook kees@kernel.org 2026-02-21T07:49:23+00:00 69050f8d6d075dc01af7a5f2f550a8067510366f This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook <kees@kernel.org> 
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook <kees@kernel.org>
net: bridge: mcast: always update mdb_n_entries for vlan contexts 2026-02-17T12:00:14+00:00 Nikolay Aleksandrov nikolay@nvidia.com 2026-02-13T07:00:30+00:00 8b769e311a86bb9d15c5658ad283b86fc8f080a2 syzbot triggered a warning[1] about the number of mdb entries in a context. It turned out that there are multiple ways to trigger that warning today (some got added during the years), the root cause of the problem is that the increase is done conditionally, and over the years these different conditions increased so there were new ways to trigger the warning, that is to do a decrease which wasn't paired with a previous increase. For example one way to trigger it is with flush: $ ip l add br0 up type bridge vlan_filtering 1 mcast_snooping 1 $ ip l add dumdum up master br0 type dummy $ bridge mdb add dev br0 port dumdum grp 239.0.0.1 permanent vid 1 $ ip link set dev br0 down $ ip link set dev br0 type bridge mcast_vlan_snooping 1 ^^^^ this will enable snooping, but will not update mdb_n_entries because in __br_multicast_enable_port_ctx() we check !netif_running $ bridge mdb flush dev br0 ^^^ this will trigger the warning because it will delete the pg which we added above, which will try to decrease mdb_n_entries Fix the problem by removing the conditional increase and always keep the count up-to-date while the vlan exists. In order to do that we have to first initialize it on port-vlan context creation, and then always increase or decrease the value regardless of mcast options. To keep the current behaviour we have to enforce the mdb limit only if the context is port's or if the port-vlan's mcast snooping is enabled. [1] ------------[ cut here ]------------ n == 0 WARNING: net/bridge/br_multicast.c:718 at br_multicast_port_ngroups_dec_one net/bridge/br_multicast.c:718 [inline], CPU#0: syz.4.4607/22043 WARNING: net/bridge/br_multicast.c:718 at br_multicast_port_ngroups_dec net/bridge/br_multicast.c:771 [inline], CPU#0: syz.4.4607/22043 WARNING: net/bridge/br_multicast.c:718 at br_multicast_del_pg+0x1bbe/0x1e20 net/bridge/br_multicast.c:825, CPU#0: syz.4.4607/22043 Modules linked in: CPU: 0 UID: 0 PID: 22043 Comm: syz.4.4607 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026 RIP: 0010:br_multicast_port_ngroups_dec_one net/bridge/br_multicast.c:718 [inline] RIP: 0010:br_multicast_port_ngroups_dec net/bridge/br_multicast.c:771 [inline] RIP: 0010:br_multicast_del_pg+0x1bbe/0x1e20 net/bridge/br_multicast.c:825 Code: 41 5f 5d e9 04 7a 48 f7 e8 3f 73 5c f7 90 0f 0b 90 e9 cf fd ff ff e8 31 73 5c f7 90 0f 0b 90 e9 16 fd ff ff e8 23 73 5c f7 90 <0f> 0b 90 e9 60 fd ff ff e8 15 73 5c f7 eb 05 e8 0e 73 5c f7 48 8b RSP: 0018:ffffc9000c207220 EFLAGS: 00010293 RAX: ffffffff8a68042d RBX: ffff88807c6f1800 RCX: ffff888066e90000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffff888066e90000 R09: 000000000000000c R10: 000000000000000c R11: 0000000000000000 R12: ffff8880303ef800 R13: dffffc0000000000 R14: ffff888050eb11c4 R15: 1ffff1100a1d6238 FS: 00007fa45921b6c0(0000) GS:ffff8881256f5000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fa4591f9ff8 CR3: 0000000081df2000 CR4: 00000000003526f0 Call Trace: <TASK> br_mdb_flush_pgs net/bridge/br_mdb.c:1525 [inline] br_mdb_flush net/bridge/br_mdb.c:1544 [inline] br_mdb_del_bulk+0x5e2/0xb20 net/bridge/br_mdb.c:1561 rtnl_mdb_del+0x48a/0x640 net/core/rtnetlink.c:-1 rtnetlink_rcv_msg+0x77e/0xbe0 net/core/rtnetlink.c:6967 netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline] netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344 netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894 sock_sendmsg_nosec net/socket.c:727 [inline] __sock_sendmsg net/socket.c:742 [inline] ____sys_sendmsg+0xa68/0xad0 net/socket.c:2592 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646 __sys_sendmsg net/socket.c:2678 [inline] __do_sys_sendmsg net/socket.c:2683 [inline] __se_sys_sendmsg net/socket.c:2681 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fa45839aeb9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fa45921b028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007fa458615fa0 RCX: 00007fa45839aeb9 RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 0000000000000004 RBP: 00007fa458408c1f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fa458616038 R14: 00007fa458615fa0 R15: 00007fff0b59fae8 </TASK> Fixes: b57e8d870d52 ("net: bridge: Maintain number of MDB entries in net_bridge_mcast_port") Reported-by: syzbot+d5d1b7343531d17bd3c5@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/aYrWbRp83MQR1ife@debil/T/#t Reviewed-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com> Link: https://patch.msgid.link/20260213070031.1400003-2-nikolay@nvidia.com Signed-off-by: Paolo Abeni <pabeni@redhat.com> 
syzbot triggered a warning[1] about the number of mdb entries in a context.
It turned out that there are multiple ways to trigger that warning today
(some got added during the years), the root cause of the problem is that
the increase is done conditionally, and over the years these different
conditions increased so there were new ways to trigger the warning, that is
to do a decrease which wasn't paired with a previous increase.

For example one way to trigger it is with flush:
 $ ip l add br0 up type bridge vlan_filtering 1 mcast_snooping 1
 $ ip l add dumdum up master br0 type dummy
 $ bridge mdb add dev br0 port dumdum grp 239.0.0.1 permanent vid 1
 $ ip link set dev br0 down
 $ ip link set dev br0 type bridge mcast_vlan_snooping 1
   ^^^^ this will enable snooping, but will not update mdb_n_entries
        because in __br_multicast_enable_port_ctx() we check !netif_running
 $ bridge mdb flush dev br0
   ^^^ this will trigger the warning because it will delete the pg which
       we added above, which will try to decrease mdb_n_entries

Fix the problem by removing the conditional increase and always keep the
count up-to-date while the vlan exists. In order to do that we have to
first initialize it on port-vlan context creation, and then always increase
or decrease the value regardless of mcast options. To keep the current
behaviour we have to enforce the mdb limit only if the context is port's or
if the port-vlan's mcast snooping is enabled.

[1]
 ------------[ cut here ]------------
 n == 0
 WARNING: net/bridge/br_multicast.c:718 at br_multicast_port_ngroups_dec_one net/bridge/br_multicast.c:718 [inline], CPU#0: syz.4.4607/22043
 WARNING: net/bridge/br_multicast.c:718 at br_multicast_port_ngroups_dec net/bridge/br_multicast.c:771 [inline], CPU#0: syz.4.4607/22043
 WARNING: net/bridge/br_multicast.c:718 at br_multicast_del_pg+0x1bbe/0x1e20 net/bridge/br_multicast.c:825, CPU#0: syz.4.4607/22043
 Modules linked in:
 CPU: 0 UID: 0 PID: 22043 Comm: syz.4.4607 Not tainted syzkaller #0 PREEMPT(full)
 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
 RIP: 0010:br_multicast_port_ngroups_dec_one net/bridge/br_multicast.c:718 [inline]
 RIP: 0010:br_multicast_port_ngroups_dec net/bridge/br_multicast.c:771 [inline]
 RIP: 0010:br_multicast_del_pg+0x1bbe/0x1e20 net/bridge/br_multicast.c:825
 Code: 41 5f 5d e9 04 7a 48 f7 e8 3f 73 5c f7 90 0f 0b 90 e9 cf fd ff ff e8 31 73 5c f7 90 0f 0b 90 e9 16 fd ff ff e8 23 73 5c f7 90 <0f> 0b 90 e9 60 fd ff ff e8 15 73 5c f7 eb 05 e8 0e 73 5c f7 48 8b
 RSP: 0018:ffffc9000c207220 EFLAGS: 00010293
 RAX: ffffffff8a68042d RBX: ffff88807c6f1800 RCX: ffff888066e90000
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
 RBP: 0000000000000000 R08: ffff888066e90000 R09: 000000000000000c
 R10: 000000000000000c R11: 0000000000000000 R12: ffff8880303ef800
 R13: dffffc0000000000 R14: ffff888050eb11c4 R15: 1ffff1100a1d6238
 FS:  00007fa45921b6c0(0000) GS:ffff8881256f5000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fa4591f9ff8 CR3: 0000000081df2000 CR4: 00000000003526f0
 Call Trace:
  <TASK>
  br_mdb_flush_pgs net/bridge/br_mdb.c:1525 [inline]
  br_mdb_flush net/bridge/br_mdb.c:1544 [inline]
  br_mdb_del_bulk+0x5e2/0xb20 net/bridge/br_mdb.c:1561
  rtnl_mdb_del+0x48a/0x640 net/core/rtnetlink.c:-1
  rtnetlink_rcv_msg+0x77e/0xbe0 net/core/rtnetlink.c:6967
  netlink_rcv_skb+0x232/0x4b0 net/netlink/af_netlink.c:2550
  netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
  netlink_unicast+0x80f/0x9b0 net/netlink/af_netlink.c:1344
  netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1894
  sock_sendmsg_nosec net/socket.c:727 [inline]
  __sock_sendmsg net/socket.c:742 [inline]
  ____sys_sendmsg+0xa68/0xad0 net/socket.c:2592
  ___sys_sendmsg+0x2a5/0x360 net/socket.c:2646
  __sys_sendmsg net/socket.c:2678 [inline]
  __do_sys_sendmsg net/socket.c:2683 [inline]
  __se_sys_sendmsg net/socket.c:2681 [inline]
  __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2681
  do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
  do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
  entry_SYSCALL_64_after_hwframe+0x77/0x7f
 RIP: 0033:0x7fa45839aeb9
 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
 RSP: 002b:00007fa45921b028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
 RAX: ffffffffffffffda RBX: 00007fa458615fa0 RCX: 00007fa45839aeb9
 RDX: 0000000000000000 RSI: 00002000000000c0 RDI: 0000000000000004
 RBP: 00007fa458408c1f R08: 0000000000000000 R09: 0000000000000000
 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
 R13: 00007fa458616038 R14: 00007fa458615fa0 R15: 00007fff0b59fae8
 </TASK>

Fixes: b57e8d870d52 ("net: bridge: Maintain number of MDB entries in net_bridge_mcast_port")
Reported-by: syzbot+d5d1b7343531d17bd3c5@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/aYrWbRp83MQR1ife@debil/T/#t
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Link: https://patch.msgid.link/20260213070031.1400003-2-nikolay@nvidia.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
net: bridge: mcast: fix memcpy with u64_stats 2026-01-25T21:14:11+00:00 David Yang mmyangfl@gmail.com 2026-01-20T09:21:30+00:00 dd7fca9f49d3e7ab7e48d9c616bff0c84148a7e0 On 64bit arches, struct u64_stats_sync is empty and provides no help against load/store tearing. memcpy() should not be considered atomic against u64 values. Use u64_stats_copy() instead. Signed-off-by: David Yang <mmyangfl@gmail.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20260120092137.2161162-3-mmyangfl@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
On 64bit arches, struct u64_stats_sync is empty and provides no help
against load/store tearing. memcpy() should not be considered atomic
against u64 values. Use u64_stats_copy() instead.

Signed-off-by: David Yang <mmyangfl@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260120092137.2161162-3-mmyangfl@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: bridge: Flush multicast groups when snooping is disabled 2025-10-28T00:57:21+00:00 Petr Machata petrm@nvidia.com 2025-10-23T14:45:37+00:00 68800bbf583f26f71491141e4b3c8582f9cfcbde When forwarding multicast packets, the bridge takes MDB into account when IGMP / MLD snooping is enabled. Currently, when snooping is disabled, the MDB is retained, even though it is not used anymore. At the same time, during the time that snooping is disabled, the IGMP / MLD control packets are obviously ignored, and after the snooping is reenabled, the administrator has to assume it is out of sync. In particular, missed join and leave messages would lead to traffic being forwarded to wrong interfaces. Keeping the MDB entries around thus serves no purpose, and just takes memory. Note also that disabling per-VLAN snooping does actually flush the relevant MDB entries. This patch flushes non-permanent MDB entries as global snooping is disabled. Signed-off-by: Petr Machata <petrm@nvidia.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Link: https://patch.msgid.link/5e992df1bb93b88e19c0ea5819e23b669e3dde5d.1761228273.git.petrm@nvidia.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
When forwarding multicast packets, the bridge takes MDB into account when
IGMP / MLD snooping is enabled. Currently, when snooping is disabled, the
MDB is retained, even though it is not used anymore.

At the same time, during the time that snooping is disabled, the IGMP / MLD
control packets are obviously ignored, and after the snooping is reenabled,
the administrator has to assume it is out of sync. In particular, missed
join and leave messages would lead to traffic being forwarded to wrong
interfaces.

Keeping the MDB entries around thus serves no purpose, and just takes
memory. Note also that disabling per-VLAN snooping does actually flush the
relevant MDB entries.

This patch flushes non-permanent MDB entries as global snooping is
disabled.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/5e992df1bb93b88e19c0ea5819e23b669e3dde5d.1761228273.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2025-08-21T18:33:15+00:00 Jakub Kicinski kuba@kernel.org 2025-06-12T17:08:24+00:00 a9af709fda7edafa17e072bffe610d9e7ed7a5df Cross-merge networking fixes after downstream PR (net-6.17-rc3). No conflicts or adjacent changes. Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Cross-merge networking fixes after downstream PR (net-6.17-rc3).

No conflicts or adjacent changes.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: bridge: remove unused argument of br_multicast_query_expired() 2025-08-15T17:26:56+00:00 Wang Liang wangliang74@huawei.com 2025-08-14T04:23:55+00:00 7de0eebbb4c3bb44c296f66679ad37480139dc6e Since commit 67b746f94ff3 ("net: bridge: mcast: make sure querier port/address updates are consistent"), the argument 'querier' is unused, just get rid of it. Signed-off-by: Wang Liang <wangliang74@huawei.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Link: https://patch.msgid.link/20250814042355.1720755-1-wangliang74@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Since commit 67b746f94ff3 ("net: bridge: mcast: make sure querier
port/address updates are consistent"), the argument 'querier' is unused,
just get rid of it.

Signed-off-by: Wang Liang <wangliang74@huawei.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20250814042355.1720755-1-wangliang74@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: bridge: fix soft lockup in br_multicast_query_expired() 2025-08-15T00:49:33+00:00 Wang Liang wangliang74@huawei.com 2025-08-13T02:10:54+00:00 d1547bf460baec718b3398365f8de33d25c5f36f When set multicast_query_interval to a large value, the local variable 'time' in br_multicast_send_query() may overflow. If the time is smaller than jiffies, the timer will expire immediately, and then call mod_timer() again, which creates a loop and may trigger the following soft lockup issue. watchdog: BUG: soft lockup - CPU#1 stuck for 221s! [rb_consumer:66] CPU: 1 UID: 0 PID: 66 Comm: rb_consumer Not tainted 6.16.0+ #259 PREEMPT(none) Call Trace: <IRQ> __netdev_alloc_skb+0x2e/0x3a0 br_ip6_multicast_alloc_query+0x212/0x1b70 __br_multicast_send_query+0x376/0xac0 br_multicast_send_query+0x299/0x510 br_multicast_query_expired.constprop.0+0x16d/0x1b0 call_timer_fn+0x3b/0x2a0 __run_timers+0x619/0x950 run_timer_softirq+0x11c/0x220 handle_softirqs+0x18e/0x560 __irq_exit_rcu+0x158/0x1a0 sysvec_apic_timer_interrupt+0x76/0x90 </IRQ> This issue can be reproduced with: ip link add br0 type bridge echo 1 > /sys/class/net/br0/bridge/multicast_querier echo 0xffffffffffffffff > /sys/class/net/br0/bridge/multicast_query_interval ip link set dev br0 up The multicast_startup_query_interval can also cause this issue. Similar to the commit 99b40610956a ("net: bridge: mcast: add and enforce query interval minimum"), add check for the query interval maximum to fix this issue. Link: https://lore.kernel.org/netdev/20250806094941.1285944-1-wangliang74@huawei.com/ Link: https://lore.kernel.org/netdev/20250812091818.542238-1-wangliang74@huawei.com/ Fixes: d902eee43f19 ("bridge: Add multicast count/interval sysfs entries") Suggested-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Wang Liang <wangliang74@huawei.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Acked-by: Nikolay Aleksandrov <razor@blackwall.org> Link: https://patch.msgid.link/20250813021054.1643649-1-wangliang74@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
When set multicast_query_interval to a large value, the local variable
'time' in br_multicast_send_query() may overflow. If the time is smaller
than jiffies, the timer will expire immediately, and then call mod_timer()
again, which creates a loop and may trigger the following soft lockup
issue.

  watchdog: BUG: soft lockup - CPU#1 stuck for 221s! [rb_consumer:66]
  CPU: 1 UID: 0 PID: 66 Comm: rb_consumer Not tainted 6.16.0+ #259 PREEMPT(none)
  Call Trace:
   <IRQ>
   __netdev_alloc_skb+0x2e/0x3a0
   br_ip6_multicast_alloc_query+0x212/0x1b70
   __br_multicast_send_query+0x376/0xac0
   br_multicast_send_query+0x299/0x510
   br_multicast_query_expired.constprop.0+0x16d/0x1b0
   call_timer_fn+0x3b/0x2a0
   __run_timers+0x619/0x950
   run_timer_softirq+0x11c/0x220
   handle_softirqs+0x18e/0x560
   __irq_exit_rcu+0x158/0x1a0
   sysvec_apic_timer_interrupt+0x76/0x90
   </IRQ>

This issue can be reproduced with:
  ip link add br0 type bridge
  echo 1 > /sys/class/net/br0/bridge/multicast_querier
  echo 0xffffffffffffffff >
  	/sys/class/net/br0/bridge/multicast_query_interval
  ip link set dev br0 up

The multicast_startup_query_interval can also cause this issue. Similar to
the commit 99b40610956a ("net: bridge: mcast: add and enforce query
interval minimum"), add check for the query interval maximum to fix this
issue.

Link: https://lore.kernel.org/netdev/20250806094941.1285944-1-wangliang74@huawei.com/
Link: https://lore.kernel.org/netdev/20250812091818.542238-1-wangliang74@huawei.com/
Fixes: d902eee43f19 ("bridge: Add multicast count/interval sysfs entries")
Suggested-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Wang Liang <wangliang74@huawei.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/20250813021054.1643649-1-wangliang74@huawei.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
bridge: mcast: Fix use-after-free during router port configuration 2025-06-24T01:19:10+00:00 Ido Schimmel idosch@nvidia.com 2025-06-19T18:22:28+00:00 7544f3f5b0b58c396f374d060898b5939da31709 The bridge maintains a global list of ports behind which a multicast router resides. The list is consulted during forwarding to ensure multicast packets are forwarded to these ports even if the ports are not member in the matching MDB entry. When per-VLAN multicast snooping is enabled, the per-port multicast context is disabled on each port and the port is removed from the global router port list: # ip link add name br1 up type bridge vlan_filtering 1 mcast_snooping 1 # ip link add name dummy1 up master br1 type dummy # ip link set dev dummy1 type bridge_slave mcast_router 2 $ bridge -d mdb show | grep router router ports on br1: dummy1 # ip link set dev br1 type bridge mcast_vlan_snooping 1 $ bridge -d mdb show | grep router However, the port can be re-added to the global list even when per-VLAN multicast snooping is enabled: # ip link set dev dummy1 type bridge_slave mcast_router 0 # ip link set dev dummy1 type bridge_slave mcast_router 2 $ bridge -d mdb show | grep router router ports on br1: dummy1 Since commit 4b30ae9adb04 ("net: bridge: mcast: re-implement br_multicast_{enable, disable}_port functions"), when per-VLAN multicast snooping is enabled, multicast disablement on a port will disable the per-{port, VLAN} multicast contexts and not the per-port one. As a result, a port will remain in the global router port list even after it is deleted. This will lead to a use-after-free [1] when the list is traversed (when adding a new port to the list, for example): # ip link del dev dummy1 # ip link add name dummy2 up master br1 type dummy # ip link set dev dummy2 type bridge_slave mcast_router 2 Similarly, stale entries can also be found in the per-VLAN router port list. When per-VLAN multicast snooping is disabled, the per-{port, VLAN} contexts are disabled on each port and the port is removed from the per-VLAN router port list: # ip link add name br1 up type bridge vlan_filtering 1 mcast_snooping 1 mcast_vlan_snooping 1 # ip link add name dummy1 up master br1 type dummy # bridge vlan add vid 2 dev dummy1 # bridge vlan global set vid 2 dev br1 mcast_snooping 1 # bridge vlan set vid 2 dev dummy1 mcast_router 2 $ bridge vlan global show dev br1 vid 2 | grep router router ports: dummy1 # ip link set dev br1 type bridge mcast_vlan_snooping 0 $ bridge vlan global show dev br1 vid 2 | grep router However, the port can be re-added to the per-VLAN list even when per-VLAN multicast snooping is disabled: # bridge vlan set vid 2 dev dummy1 mcast_router 0 # bridge vlan set vid 2 dev dummy1 mcast_router 2 $ bridge vlan global show dev br1 vid 2 | grep router router ports: dummy1 When the VLAN is deleted from the port, the per-{port, VLAN} multicast context will not be disabled since multicast snooping is not enabled on the VLAN. As a result, the port will remain in the per-VLAN router port list even after it is no longer member in the VLAN. This will lead to a use-after-free [2] when the list is traversed (when adding a new port to the list, for example): # ip link add name dummy2 up master br1 type dummy # bridge vlan add vid 2 dev dummy2 # bridge vlan del vid 2 dev dummy1 # bridge vlan set vid 2 dev dummy2 mcast_router 2 Fix these issues by removing the port from the relevant (global or per-VLAN) router port list in br_multicast_port_ctx_deinit(). The function is invoked during port deletion with the per-port multicast context and during VLAN deletion with the per-{port, VLAN} multicast context. Note that deleting the multicast router timer is not enough as it only takes care of the temporary multicast router states (1 or 3) and not the permanent one (2). [1] BUG: KASAN: slab-out-of-bounds in br_multicast_add_router.part.0+0x3f1/0x560 Write of size 8 at addr ffff888004a67328 by task ip/384 [...] Call Trace: <TASK> dump_stack_lvl+0x6f/0xa0 print_address_description.constprop.0+0x6f/0x350 print_report+0x108/0x205 kasan_report+0xdf/0x110 br_multicast_add_router.part.0+0x3f1/0x560 br_multicast_set_port_router+0x74e/0xac0 br_setport+0xa55/0x1870 br_port_slave_changelink+0x95/0x120 __rtnl_newlink+0x5e8/0xa40 rtnl_newlink+0x627/0xb00 rtnetlink_rcv_msg+0x6fb/0xb70 netlink_rcv_skb+0x11f/0x350 netlink_unicast+0x426/0x710 netlink_sendmsg+0x75a/0xc20 __sock_sendmsg+0xc1/0x150 ____sys_sendmsg+0x5aa/0x7b0 ___sys_sendmsg+0xfc/0x180 __sys_sendmsg+0x124/0x1c0 do_syscall_64+0xbb/0x360 entry_SYSCALL_64_after_hwframe+0x4b/0x53 [2] BUG: KASAN: slab-use-after-free in br_multicast_add_router.part.0+0x378/0x560 Read of size 8 at addr ffff888009f00840 by task bridge/391 [...] Call Trace: <TASK> dump_stack_lvl+0x6f/0xa0 print_address_description.constprop.0+0x6f/0x350 print_report+0x108/0x205 kasan_report+0xdf/0x110 br_multicast_add_router.part.0+0x378/0x560 br_multicast_set_port_router+0x6f9/0xac0 br_vlan_process_options+0x8b6/0x1430 br_vlan_rtm_process_one+0x605/0xa30 br_vlan_rtm_process+0x396/0x4c0 rtnetlink_rcv_msg+0x2f7/0xb70 netlink_rcv_skb+0x11f/0x350 netlink_unicast+0x426/0x710 netlink_sendmsg+0x75a/0xc20 __sock_sendmsg+0xc1/0x150 ____sys_sendmsg+0x5aa/0x7b0 ___sys_sendmsg+0xfc/0x180 __sys_sendmsg+0x124/0x1c0 do_syscall_64+0xbb/0x360 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Fixes: 2796d846d74a ("net: bridge: vlan: convert mcast router global option to per-vlan entry") Fixes: 4b30ae9adb04 ("net: bridge: mcast: re-implement br_multicast_{enable, disable}_port functions") Reported-by: syzbot+7bfa4b72c6a5da128d32@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/684c18bd.a00a0220.279073.000b.GAE@google.com/T/ Signed-off-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20250619182228.1656906-1-idosch@nvidia.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
The bridge maintains a global list of ports behind which a multicast
router resides. The list is consulted during forwarding to ensure
multicast packets are forwarded to these ports even if the ports are not
member in the matching MDB entry.

When per-VLAN multicast snooping is enabled, the per-port multicast
context is disabled on each port and the port is removed from the global
router port list:

 # ip link add name br1 up type bridge vlan_filtering 1 mcast_snooping 1
 # ip link add name dummy1 up master br1 type dummy
 # ip link set dev dummy1 type bridge_slave mcast_router 2
 $ bridge -d mdb show | grep router
 router ports on br1: dummy1
 # ip link set dev br1 type bridge mcast_vlan_snooping 1
 $ bridge -d mdb show | grep router

However, the port can be re-added to the global list even when per-VLAN
multicast snooping is enabled:

 # ip link set dev dummy1 type bridge_slave mcast_router 0
 # ip link set dev dummy1 type bridge_slave mcast_router 2
 $ bridge -d mdb show | grep router
 router ports on br1: dummy1

Since commit 4b30ae9adb04 ("net: bridge: mcast: re-implement
br_multicast_{enable, disable}_port functions"), when per-VLAN multicast
snooping is enabled, multicast disablement on a port will disable the
per-{port, VLAN} multicast contexts and not the per-port one. As a
result, a port will remain in the global router port list even after it
is deleted. This will lead to a use-after-free [1] when the list is
traversed (when adding a new port to the list, for example):

 # ip link del dev dummy1
 # ip link add name dummy2 up master br1 type dummy
 # ip link set dev dummy2 type bridge_slave mcast_router 2

Similarly, stale entries can also be found in the per-VLAN router port
list. When per-VLAN multicast snooping is disabled, the per-{port, VLAN}
contexts are disabled on each port and the port is removed from the
per-VLAN router port list:

 # ip link add name br1 up type bridge vlan_filtering 1 mcast_snooping 1 mcast_vlan_snooping 1
 # ip link add name dummy1 up master br1 type dummy
 # bridge vlan add vid 2 dev dummy1
 # bridge vlan global set vid 2 dev br1 mcast_snooping 1
 # bridge vlan set vid 2 dev dummy1 mcast_router 2
 $ bridge vlan global show dev br1 vid 2 | grep router
       router ports: dummy1
 # ip link set dev br1 type bridge mcast_vlan_snooping 0
 $ bridge vlan global show dev br1 vid 2 | grep router

However, the port can be re-added to the per-VLAN list even when
per-VLAN multicast snooping is disabled:

 # bridge vlan set vid 2 dev dummy1 mcast_router 0
 # bridge vlan set vid 2 dev dummy1 mcast_router 2
 $ bridge vlan global show dev br1 vid 2 | grep router
       router ports: dummy1

When the VLAN is deleted from the port, the per-{port, VLAN} multicast
context will not be disabled since multicast snooping is not enabled
on the VLAN. As a result, the port will remain in the per-VLAN router
port list even after it is no longer member in the VLAN. This will lead
to a use-after-free [2] when the list is traversed (when adding a new
port to the list, for example):

 # ip link add name dummy2 up master br1 type dummy
 # bridge vlan add vid 2 dev dummy2
 # bridge vlan del vid 2 dev dummy1
 # bridge vlan set vid 2 dev dummy2 mcast_router 2

Fix these issues by removing the port from the relevant (global or
per-VLAN) router port list in br_multicast_port_ctx_deinit(). The
function is invoked during port deletion with the per-port multicast
context and during VLAN deletion with the per-{port, VLAN} multicast
context.

Note that deleting the multicast router timer is not enough as it only
takes care of the temporary multicast router states (1 or 3) and not the
permanent one (2).

[1]
BUG: KASAN: slab-out-of-bounds in br_multicast_add_router.part.0+0x3f1/0x560
Write of size 8 at addr ffff888004a67328 by task ip/384
[...]
Call Trace:
 <TASK>
 dump_stack_lvl+0x6f/0xa0
 print_address_description.constprop.0+0x6f/0x350
 print_report+0x108/0x205
 kasan_report+0xdf/0x110
 br_multicast_add_router.part.0+0x3f1/0x560
 br_multicast_set_port_router+0x74e/0xac0
 br_setport+0xa55/0x1870
 br_port_slave_changelink+0x95/0x120
 __rtnl_newlink+0x5e8/0xa40
 rtnl_newlink+0x627/0xb00
 rtnetlink_rcv_msg+0x6fb/0xb70
 netlink_rcv_skb+0x11f/0x350
 netlink_unicast+0x426/0x710
 netlink_sendmsg+0x75a/0xc20
 __sock_sendmsg+0xc1/0x150
 ____sys_sendmsg+0x5aa/0x7b0
 ___sys_sendmsg+0xfc/0x180
 __sys_sendmsg+0x124/0x1c0
 do_syscall_64+0xbb/0x360
 entry_SYSCALL_64_after_hwframe+0x4b/0x53

[2]
BUG: KASAN: slab-use-after-free in br_multicast_add_router.part.0+0x378/0x560
Read of size 8 at addr ffff888009f00840 by task bridge/391
[...]
Call Trace:
 <TASK>
 dump_stack_lvl+0x6f/0xa0
 print_address_description.constprop.0+0x6f/0x350
 print_report+0x108/0x205
 kasan_report+0xdf/0x110
 br_multicast_add_router.part.0+0x378/0x560
 br_multicast_set_port_router+0x6f9/0xac0
 br_vlan_process_options+0x8b6/0x1430
 br_vlan_rtm_process_one+0x605/0xa30
 br_vlan_rtm_process+0x396/0x4c0
 rtnetlink_rcv_msg+0x2f7/0xb70
 netlink_rcv_skb+0x11f/0x350
 netlink_unicast+0x426/0x710
 netlink_sendmsg+0x75a/0xc20
 __sock_sendmsg+0xc1/0x150
 ____sys_sendmsg+0x5aa/0x7b0
 ___sys_sendmsg+0xfc/0x180
 __sys_sendmsg+0x124/0x1c0
 do_syscall_64+0xbb/0x360
 entry_SYSCALL_64_after_hwframe+0x4b/0x53

Fixes: 2796d846d74a ("net: bridge: vlan: convert mcast router global option to per-vlan entry")
Fixes: 4b30ae9adb04 ("net: bridge: mcast: re-implement br_multicast_{enable, disable}_port functions")
Reported-by: syzbot+7bfa4b72c6a5da128d32@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/684c18bd.a00a0220.279073.000b.GAE@google.com/T/
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20250619182228.1656906-1-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
treewide, timers: Rename from_timer() to timer_container_of() 2025-06-08T07:07:37+00:00 Ingo Molnar mingo@kernel.org 2025-05-09T05:51:14+00:00 41cb08555c4164996d67c78b3bf1c658075b75f1 Move this API to the canonical timer_*() namespace. [ tglx: Redone against pre rc1 ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com 
Move this API to the canonical timer_*() namespace.

[ tglx: Redone against pre rc1 ]

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com