kernel/linux.git/net/ipv4/arp.c, branch v6.6.131

arp: do not assume dev_hard_header() does not change skb->head

2026-01-17T15:29:59+00:00

[ Upstream commit c92510f5e3f82ba11c95991824a41e59a9c5ed81 ] arp_create() is the only dev_hard_header() caller making assumption about skb->head being unchanged. A recent commit broke this assumption. Initialize @arp pointer after dev_hard_header() call. Fixes: db5b4e39c4e6 ("ip6_gre: make ip6gre_header() robust") Reported-by: syzbot+58b44a770a1585795351@syzkaller.appspotmail.com Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20260107212250.384552-1-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

arp: switch to dev_getbyhwaddr() in arp_req_set_public()

2025-02-27T12:10:49+00:00

[ Upstream commit 4eae0ee0f1e6256d0b0b9dd6e72f1d9cf8f72e08 ] The arp_req_set_public() function is called with the rtnl lock held, which provides enough synchronization protection. This makes the RCU variant of dev_getbyhwaddr() unnecessary. Switch to using the simpler dev_getbyhwaddr() function since we already have the required rtnl locking. This change helps maintain consistency in the networking code by using the appropriate helper function for the existing locking context. Since we're not holding the RCU read lock in arp_req_set_public() existing code could trigger false positive locking warnings. Fixes: 941666c2e3e0 ("net: RCU conversion of dev_getbyhwaddr() and arp_ioctl()") Suggested-by: Kuniyuki Iwashima Reviewed-by: Kuniyuki Iwashima Signed-off-by: Breno Leitao Link: https://patch.msgid.link/20250218-arm_fix_selftest-v5-2-d3d6892db9e1@debian.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

arp: use RCU protection in arp_xmit()

2025-02-21T12:57:23+00:00

[ Upstream commit a42b69f692165ec39db42d595f4f65a4c8f42e44 ] arp_xmit() can be called without RTNL or RCU protection. Use RCU protection to avoid potential UAF. Fixes: 29a26a568038 ("netfilter: Pass struct net into the netfilter hooks") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250207135841.1948589-5-edumazet@google.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

arp: Prevent overflow in arp_req_get().

2024-03-01T12:35:08+00:00

[ Upstream commit a7d6027790acea24446ddd6632d394096c0f4667 ] syzkaller reported an overflown write in arp_req_get(). [0] When ioctl(SIOCGARP) is issued, arp_req_get() looks up an neighbour entry and copies neigh->ha to struct arpreq.arp_ha.sa_data. The arp_ha here is struct sockaddr, not struct sockaddr_storage, so the sa_data buffer is just 14 bytes. In the splat below, 2 bytes are overflown to the next int field, arp_flags. We initialise the field just after the memcpy(), so it's not a problem. However, when dev->addr_len is greater than 22 (e.g. MAX_ADDR_LEN), arp_netmask is overwritten, which could be set as htonl(0xFFFFFFFFUL) in arp_ioctl() before calling arp_req_get(). To avoid the overflow, let's limit the max length of memcpy(). Note that commit b5f0de6df6dc ("net: dev: Convert sa_data to flexible array in struct sockaddr") just silenced syzkaller. [0]: memcpy: detected field-spanning write (size 16) of single field "r->arp_ha.sa_data" at net/ipv4/arp.c:1128 (size 14) WARNING: CPU: 0 PID: 144638 at net/ipv4/arp.c:1128 arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128 Modules linked in: CPU: 0 PID: 144638 Comm: syz-executor.4 Not tainted 6.1.74 #31 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-5 04/01/2014 RIP: 0010:arp_req_get+0x411/0x4a0 net/ipv4/arp.c:1128 Code: fd ff ff e8 41 42 de fb b9 0e 00 00 00 4c 89 fe 48 c7 c2 20 6d ab 87 48 c7 c7 80 6d ab 87 c6 05 25 af 72 04 01 e8 5f 8d ad fb <0f> 0b e9 6c fd ff ff e8 13 42 de fb be 03 00 00 00 4c 89 e7 e8 a6 RSP: 0018:ffffc900050b7998 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff88803a815000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8641a44a RDI: 0000000000000001 RBP: ffffc900050b7a98 R08: 0000000000000001 R09: 0000000000000000 R10: 0000000000000000 R11: 203a7970636d656d R12: ffff888039c54000 R13: 1ffff92000a16f37 R14: ffff88803a815084 R15: 0000000000000010 FS: 00007f172bf306c0(0000) GS:ffff88805aa00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f172b3569f0 CR3: 0000000057f12005 CR4: 0000000000770ef0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: arp_ioctl+0x33f/0x4b0 net/ipv4/arp.c:1261 inet_ioctl+0x314/0x3a0 net/ipv4/af_inet.c:981 sock_do_ioctl+0xdf/0x260 net/socket.c:1204 sock_ioctl+0x3ef/0x650 net/socket.c:1321 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x18e/0x220 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x37/0x90 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x64/0xce RIP: 0033:0x7f172b262b8d Code: 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 f3 0f 1e fa 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f172bf300b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f172b3abf80 RCX: 00007f172b262b8d RDX: 0000000020000000 RSI: 0000000000008954 RDI: 0000000000000003 RBP: 00007f172b2d3493 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f172b3abf80 R15: 00007f172bf10000 Reported-by: syzkaller Reported-by: Bjoern Doebel Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Link: https://lore.kernel.org/r/20240215230516.31330-1-kuniyu@amazon.com Signed-off-by: Paolo Abeni Signed-off-by: Sasha Levin

neighbour: annotate lockless accesses to n->nud_state

2023-03-15T07:37:32+00:00

We have many lockless accesses to n->nud_state. Before adding another one in the following patch, add annotations to readers and writers. Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Martin KaFai Lau Signed-off-by: Jakub Kicinski

ipv4: move from strlcpy with unused retval to strscpy

2022-08-23T00:59:37+00:00

Follow the advice of the below link and prefer 'strscpy' in this subsystem. Conversion is 1:1 because the return value is not used. Generated by a coccinelle script. Link: https://lore.kernel.org/r/CAHk-=wgfRnXz0W3D37d01q3JFkr_i_uTL=V6A6G1oUZcprmknw@mail.gmail.com/ Signed-off-by: Wolfram Sang Link: https://lore.kernel.org/r/20220818210219.8467-1-wsa+renesas@sang-engineering.com Signed-off-by: Jakub Kicinski

net: ipv4: new arp_accept option to accept garp only if in-network

2022-07-16T01:55:49+00:00

In many deployments, we want the option to not learn a neighbor from garp if the src ip is not in the same subnet as an address configured on the interface that received the garp message. net.ipv4.arp_accept sysctl is currently used to control creation of a neigh from a received garp packet. This patch adds a new option '2' to net.ipv4.arp_accept which extends option '1' by including the subnet check. Signed-off-by: Jaehee Park Suggested-by: Roopa Prabhu Signed-off-by: Jakub Kicinski

net, neigh: introduce interval_probe_time_ms for periodic probe

2022-06-30T11:14:35+00:00

commit ed6cd6a17896 ("net, neigh: Set lower cap for neigh_managed_work rearming") fixed a case when DELAY_PROBE_TIME is configured to 0, the processing of the system work queue hog CPU to 100%, and further more we should introduce a new option used by periodic probe Signed-off-by: Yuwei Wang Signed-off-by: Paolo Abeni

arp: fix unused variable warnning when CONFIG_PROC_FS=n

2022-04-25T10:50:18+00:00

net/ipv4/arp.c:1412:36: warning: unused variable 'arp_seq_ops' [-Wunused-const-variable] Add #ifdef CONFIG_PROC_FS for 'arp_seq_ops'. Fixes: e968b1b3e9b8 ("arp: Remove #ifdef CONFIG_PROC_FS") Reported-by: kernel test robot Signed-off-by: Yajun Deng Signed-off-by: David S. Miller

net: neigh: add skb drop reasons to arp_error_report()

2022-02-26T12:53:59+00:00

When neighbour become invalid or destroyed, neigh_invalidate() will be called. neigh->ops->error_report() will be called if the neighbour's state is NUD_FAILED, and seems here is the only use of error_report(). So we can tell that the reason of skb drops in arp_error_report() is SKB_DROP_REASON_NEIGH_FAILED. Replace kfree_skb() used in arp_error_report() with kfree_skb_reason(). Reviewed-by: Mengen Sun Reviewed-by: Hao Peng Signed-off-by: Menglong Dong Reviewed-by: David Ahern Signed-off-by: David S. Miller