kernel/linux.git/net/bridge/netfilter, branch v5.10.259

netfilter: bridge: make ebt_snat ARP rewrite writable

2026-06-19T11:21:34+00:00

[ Upstream commit 67ba971ae02514d85818fe0c32549ab4bfa3bf49 ] The ebtables SNAT target keeps the Ethernet source address rewrite behind skb_ensure_writable(skb, 0). This is intentional: at the bridge ebtables hooks the Ethernet header is addressed through skb_mac_header()/eth_hdr(), while skb->data points at the Ethernet payload. Asking skb_ensure_writable() for ETH_HLEN bytes would check the payload, not the Ethernet header, and would reintroduce the small packet regression fixed by commit 63137bc5882a. However, the optional ARP sender hardware address rewrite is different. It writes through skb_store_bits() at an offset relative to skb->data: skb_store_bits(skb, sizeof(struct arphdr), info->mac, ETH_ALEN) skb_header_pointer() only safely reads the ARP header; it does not make the later sender hardware address range writable. If that range is still held in a nonlinear skb fragment backed by a splice-imported file page, skb_store_bits() maps the frag page and copies the new MAC address directly into it. Ensure the ARP SHA range is writable before reading the ARP header and before calling skb_store_bits(). Fixes: 63137bc5882a ("netfilter: ebtables: Fixes dropping of small packets in bridge nat") Reported-by: Yiming Qian Signed-off-by: Yiming Qian Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: ebtables: fix OOB read in compat_mtw_from_user

2026-06-19T11:21:25+00:00

[ Upstream commit f438d1786d657d57790c5d138d6db3fc9fdac392 ] Luxiao Xu says: The function compat_mtw_from_user() converts ebtables extensions from 32-bit user structures to kernel native structures. However, it lacks proper validation of the user-supplied match_size/target_size. When certain extensions are processed, the kernel-side translation logic may perform memory accesses based on the extension's expected size. If the user provides a size smaller than what the extension requires, it results in an out-of-bounds read as reported by KASAN. This fix introduces a check to ensure match_size is at least as large as the extension's required compatsize. This covers matches, watchers, and targets, while maintaining compatibility with standard targets. AFAIU this is relevant for matches that need to go though match->compat_from_user() call. Those that use plain memcpy with the user-provided size are ok because the caller checks that size vs the start of the next rule entry offset (which itself is checked vs. total size copied from userspace). The ->compat_from_user() callbacks assume they can read compatsize bytes, so they need this extra check. Based on an earlier patch from Luxiao Xu. Fixes: 81e675c227ec ("netfilter: ebtables: add CONFIG_COMPAT support") Reported-by: Yuan Tan Reported-by: Yifan Wu Reported-by: Juefei Pu Reported-by: Xin Liu Signed-off-by: Luxiao Xu Signed-off-by: Ren Wei Reviewed-by: Fernando Fernandez Mancera Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin

netfilter: nft_reject: unify reject init and dump into nft_reject

2025-08-28T14:22:59+00:00

[ Upstream commit 312ca575a50543a886a5dfa2af1e72aa6a5b601e ] Bridge family is using the same static init and dump function as inet. This patch removes duplicate code unifying these functions body into nft_reject.c so they can be reused in the rest of families supporting reject verdict. Signed-off-by: Jose M. Guisado Gomez Signed-off-by: Pablo Neira Ayuso Stable-dep-of: 91a79b792204 ("netfilter: nf_reject: don't leak dst refcount for loopback packets") Signed-off-by: Sasha Levin

netfilter: bridge: Move specific fragmented packet to slow_path instead of dropping it

2025-06-27T10:04:03+00:00

[ Upstream commit aa04c6f45b9224b949aa35d4fa5f8d0ba07b23d4 ] The config NF_CONNTRACK_BRIDGE will change the bridge forwarding for fragmented packets. The original bridge does not know that it is a fragmented packet and forwards it directly, after NF_CONNTRACK_BRIDGE is enabled, function nf_br_ip_fragment and br_ip6_fragment will check the headroom. In original br_forward, insufficient headroom of skb may indeed exist, but there's still a way to save the skb in the device driver after dev_queue_xmit.So droping the skb will change the original bridge forwarding in some cases. Fixes: 3c171f496ef5 ("netfilter: bridge: add connection tracking system") Signed-off-by: Huajian Yang Reviewed-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: validate user input for expected length

2024-04-13T10:59:25+00:00

commit 0c83842df40f86e529db6842231154772c20edcc upstream. I got multiple syzbot reports showing old bugs exposed by BPF after commit 20f2505fb436 ("bpf: Try to avoid kzalloc in cgroup/{s,g}etsockopt") setsockopt() @optlen argument should be taken into account before copying data. BUG: KASAN: slab-out-of-bounds in copy_from_sockptr_offset include/linux/sockptr.h:49 [inline] BUG: KASAN: slab-out-of-bounds in copy_from_sockptr include/linux/sockptr.h:55 [inline] BUG: KASAN: slab-out-of-bounds in do_replace net/ipv4/netfilter/ip_tables.c:1111 [inline] BUG: KASAN: slab-out-of-bounds in do_ipt_set_ctl+0x902/0x3dd0 net/ipv4/netfilter/ip_tables.c:1627 Read of size 96 at addr ffff88802cd73da0 by task syz-executor.4/7238 CPU: 1 PID: 7238 Comm: syz-executor.4 Not tainted 6.9.0-rc2-next-20240403-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105 copy_from_sockptr_offset include/linux/sockptr.h:49 [inline] copy_from_sockptr include/linux/sockptr.h:55 [inline] do_replace net/ipv4/netfilter/ip_tables.c:1111 [inline] do_ipt_set_ctl+0x902/0x3dd0 net/ipv4/netfilter/ip_tables.c:1627 nf_setsockopt+0x295/0x2c0 net/netfilter/nf_sockopt.c:101 do_sock_setsockopt+0x3af/0x720 net/socket.c:2311 __sys_setsockopt+0x1ae/0x250 net/socket.c:2334 __do_sys_setsockopt net/socket.c:2343 [inline] __se_sys_setsockopt net/socket.c:2340 [inline] __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x72/0x7a RIP: 0033:0x7fd22067dde9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fd21f9ff0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 00007fd2207abf80 RCX: 00007fd22067dde9 RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007fd2206ca47a R08: 0000000000000001 R09: 0000000000000000 R10: 0000000020000880 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007fd2207abf80 R15: 00007ffd2d0170d8 Allocated by task 7238: kasan_save_stack mm/kasan/common.c:47 [inline] kasan_save_track+0x3f/0x80 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:370 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387 kasan_kmalloc include/linux/kasan.h:211 [inline] __do_kmalloc_node mm/slub.c:4069 [inline] __kmalloc_noprof+0x200/0x410 mm/slub.c:4082 kmalloc_noprof include/linux/slab.h:664 [inline] __cgroup_bpf_run_filter_setsockopt+0xd47/0x1050 kernel/bpf/cgroup.c:1869 do_sock_setsockopt+0x6b4/0x720 net/socket.c:2293 __sys_setsockopt+0x1ae/0x250 net/socket.c:2334 __do_sys_setsockopt net/socket.c:2343 [inline] __se_sys_setsockopt net/socket.c:2340 [inline] __x64_sys_setsockopt+0xb5/0xd0 net/socket.c:2340 do_syscall_64+0xfb/0x240 entry_SYSCALL_64_after_hwframe+0x72/0x7a The buggy address belongs to the object at ffff88802cd73da0 which belongs to the cache kmalloc-8 of size 8 The buggy address is located 0 bytes inside of allocated 1-byte region [ffff88802cd73da0, ffff88802cd73da1) The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88802cd73020 pfn:0x2cd73 flags: 0xfff80000000000(node=0|zone=1|lastcpupid=0xfff) page_type: 0xffffefff(slab) raw: 00fff80000000000 ffff888015041280 dead000000000100 dead000000000122 raw: ffff88802cd73020 000000008080007f 00000001ffffefff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 5103, tgid 2119833701 (syz-executor.4), ts 5103, free_ts 70804600828 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1490 prep_new_page mm/page_alloc.c:1498 [inline] get_page_from_freelist+0x2e7e/0x2f40 mm/page_alloc.c:3454 __alloc_pages_noprof+0x256/0x6c0 mm/page_alloc.c:4712 __alloc_pages_node_noprof include/linux/gfp.h:244 [inline] alloc_pages_node_noprof include/linux/gfp.h:271 [inline] alloc_slab_page+0x5f/0x120 mm/slub.c:2249 allocate_slab+0x5a/0x2e0 mm/slub.c:2412 new_slab mm/slub.c:2465 [inline] ___slab_alloc+0xcd1/0x14b0 mm/slub.c:3615 __slab_alloc+0x58/0xa0 mm/slub.c:3705 __slab_alloc_node mm/slub.c:3758 [inline] slab_alloc_node mm/slub.c:3936 [inline] __do_kmalloc_node mm/slub.c:4068 [inline] kmalloc_node_track_caller_noprof+0x286/0x450 mm/slub.c:4089 kstrdup+0x3a/0x80 mm/util.c:62 device_rename+0xb5/0x1b0 drivers/base/core.c:4558 dev_change_name+0x275/0x860 net/core/dev.c:1232 do_setlink+0xa4b/0x41f0 net/core/rtnetlink.c:2864 __rtnl_newlink net/core/rtnetlink.c:3680 [inline] rtnl_newlink+0x180b/0x20a0 net/core/rtnetlink.c:3727 rtnetlink_rcv_msg+0x89b/0x10d0 net/core/rtnetlink.c:6594 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2559 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline] netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1361 page last free pid 5146 tgid 5146 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] free_pages_prepare mm/page_alloc.c:1110 [inline] free_unref_page+0xd3c/0xec0 mm/page_alloc.c:2617 discard_slab mm/slub.c:2511 [inline] __put_partials+0xeb/0x130 mm/slub.c:2980 put_cpu_partial+0x17c/0x250 mm/slub.c:3055 __slab_free+0x2ea/0x3d0 mm/slub.c:4254 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x9e/0x140 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook mm/slub.c:3888 [inline] slab_alloc_node mm/slub.c:3948 [inline] __do_kmalloc_node mm/slub.c:4068 [inline] __kmalloc_node_noprof+0x1d7/0x450 mm/slub.c:4076 kmalloc_node_noprof include/linux/slab.h:681 [inline] kvmalloc_node_noprof+0x72/0x190 mm/util.c:634 bucket_table_alloc lib/rhashtable.c:186 [inline] rhashtable_rehash_alloc+0x9e/0x290 lib/rhashtable.c:367 rht_deferred_worker+0x4e1/0x2440 lib/rhashtable.c:427 process_one_work kernel/workqueue.c:3218 [inline] process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3299 worker_thread+0x86d/0xd70 kernel/workqueue.c:3380 kthread+0x2f0/0x390 kernel/kthread.c:388 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243 Memory state around the buggy address: ffff88802cd73c80: 07 fc fc fc 05 fc fc fc 05 fc fc fc fa fc fc fc ffff88802cd73d00: fa fc fc fc fa fc fc fc fa fc fc fc fa fc fc fc >ffff88802cd73d80: fa fc fc fc 01 fc fc fc fa fc fc fc fa fc fc fc ^ ffff88802cd73e00: fa fc fc fc fa fc fc fc 05 fc fc fc 07 fc fc fc ffff88802cd73e80: 07 fc fc fc 07 fc fc fc 07 fc fc fc 07 fc fc fc Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot Signed-off-by: Eric Dumazet Reviewed-by: Pablo Neira Ayuso Link: https://lore.kernel.org/r/20240404122051.2303764-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

netfilter: nf_conntrack_bridge: initialize err to 0

2023-11-28T16:54:54+00:00

[ Upstream commit a44af08e3d4d7566eeea98d7a29fe06e7b9de944 ] K2CI reported a problem: consume_skb(skb); return err; [nf_br_ip_fragment() error] uninitialized symbol 'err'. err is not initialized, because returning 0 is expected, initialize err to 0. Fixes: 3c171f496ef5 ("netfilter: bridge: add connection tracking system") Reported-by: k2ci Signed-off-by: Linkui Xiao Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: ebtables: fix fortify warnings in size_entry_mwt()

2023-09-23T09:01:06+00:00

[ Upstream commit a7ed3465daa240bdf01a5420f64336fee879c09d ] When compiling with gcc 13 and CONFIG_FORTIFY_SOURCE=y, the following warning appears: In function ‘fortify_memcpy_chk’, inlined from ‘size_entry_mwt’ at net/bridge/netfilter/ebtables.c:2118:2: ./include/linux/fortify-string.h:592:25: error: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Werror=attribute-warning] 592 | __read_overflow2_field(q_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The compiler is complaining: memcpy(&offsets[1], &entry->watchers_offset, sizeof(offsets) - sizeof(offsets[0])); where memcpy reads beyong &entry->watchers_offset to copy {watchers,target,next}_offset altogether into offsets[]. Silence the warning by wrapping these three up via struct_group(). Signed-off-by: GONG, Ruiqi Reviewed-by: Gustavo A. R. Silva Reviewed-by: Kees Cook Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin

netfilter: ebtables: fix table blob use-after-free

2023-03-11T15:40:12+00:00

[ Upstream commit e58a171d35e32e6e8c37cfe0e8a94406732a331f ] We are not allowed to return an error at this point. Looking at the code it looks like ret is always 0 at this point, but its not. t = find_table_lock(net, repl->name, &ret, &ebt_mutex); ... this can return a valid table, with ret != 0. This bug causes update of table->private with the new blob, but then frees the blob right away in the caller. Syzbot report: BUG: KASAN: vmalloc-out-of-bounds in __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168 Read of size 4 at addr ffffc90005425000 by task kworker/u4:4/74 Workqueue: netns cleanup_net Call Trace: kasan_report+0xbf/0x1f0 mm/kasan/report.c:517 __ebt_unregister_table+0xc00/0xcd0 net/bridge/netfilter/ebtables.c:1168 ebt_unregister_table+0x35/0x40 net/bridge/netfilter/ebtables.c:1372 ops_exit_list+0xb0/0x170 net/core/net_namespace.c:169 cleanup_net+0x4ee/0xb10 net/core/net_namespace.c:613 ... ip(6)tables appears to be ok (ret should be 0 at this point) but make this more obvious. Fixes: c58dd2dd443c ("netfilter: Can't fail and free after table replacement") Reported-by: syzbot+f61594de72d6705aea03@syzkaller.appspotmail.com Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin

netfilter: ebtables: fix memory leak when blob is malformed

2022-09-28T09:10:36+00:00

[ Upstream commit 62ce44c4fff947eebdf10bb582267e686e6835c9 ] The bug fix was incomplete, it "replaced" crash with a memory leak. The old code had an assignment to "ret" embedded into the conditional, restore this. Fixes: 7997eff82828 ("netfilter: ebtables: reject blobs that don't provide all entry points") Reported-and-tested-by: syzbot+a24c5252f3e3ab733464@syzkaller.appspotmail.com Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin

netfilter: ebtables: reject blobs that don't provide all entry points

2022-08-31T15:15:17+00:00

[ Upstream commit 7997eff82828304b780dc0a39707e1946d6f1ebf ] Harshit Mogalapalli says: In ebt_do_table() function dereferencing 'private->hook_entry[hook]' can lead to NULL pointer dereference. [..] Kernel panic: general protection fault, probably for non-canonical address 0xdffffc0000000005: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000028-0x000000000000002f] [..] RIP: 0010:ebt_do_table+0x1dc/0x1ce0 Code: 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 5c 16 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 6c df 08 48 8d 7d 2c 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 88 [..] Call Trace: nf_hook_slow+0xb1/0x170 __br_forward+0x289/0x730 maybe_deliver+0x24b/0x380 br_flood+0xc6/0x390 br_dev_xmit+0xa2e/0x12c0 For some reason ebtables rejects blobs that provide entry points that are not supported by the table, but what it should instead reject is the opposite: blobs that DO NOT provide an entry point supported by the table. t->valid_hooks is the bitmask of hooks (input, forward ...) that will see packets. Providing an entry point that is not support is harmless (never called/used), but the inverse isn't: it results in a crash because the ebtables traverser doesn't expect a NULL blob for a location its receiving packets for. Instead of fixing all the individual checks, do what iptables is doing and reject all blobs that differ from the expected hooks. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Harshit Mogalapalli Reported-by: syzkaller Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin