syzbot

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BUG: KASAN: global-out-of-bounds in memcmp+0xc0/0xca lib/string.c:687
Read of size 1 at addr ffffffff89804b80 by task syz-executor359/3197

CPU: 1 UID: 0 PID: 3197 Comm: syz-executor359 Not tainted 6.14.0-rc1-syzkaller-g2014c95afece #0
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
[<ffffffff80072526>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:132
[<ffffffff80003206>] show_stack+0x30/0x3c arch/riscv/kernel/stacktrace.c:138
[<ffffffff8005e0c4>] __dump_stack lib/dump_stack.c:94 [inline]
[<ffffffff8005e0c4>] dump_stack_lvl+0x12e/0x1a6 lib/dump_stack.c:120
[<ffffffff8000d4ec>] print_address_description mm/kasan/report.c:378 [inline]
[<ffffffff8000d4ec>] print_report+0x28e/0x5aa mm/kasan/report.c:489
[<ffffffff80a2372a>] kasan_report+0xf0/0x214 mm/kasan/report.c:602
[<ffffffff80a25518>] __asan_report_load1_noabort+0x12/0x1a mm/kasan/report_generic.c:378
[<ffffffff86185948>] memcmp+0xc0/0xca lib/string.c:687
[<ffffffff84f21c1e>] __hw_addr_add_ex+0xee/0x676 net/core/dev_addr_lists.c:88
[<ffffffff84f23e64>] __dev_mc_add net/core/dev_addr_lists.c:868 [inline]
[<ffffffff84f23e64>] dev_mc_add+0xac/0x108 net/core/dev_addr_lists.c:886
[<ffffffff850c97b8>] mrp_init_applicant+0xe8/0x56e net/802/mrp.c:873
[<ffffffff85ce9f0e>] vlan_mvrp_init_applicant+0x26/0x30 net/8021q/vlan_mvrp.c:57
[<ffffffff85cdffbe>] register_vlan_dev+0x1b4/0x922 net/8021q/vlan.c:170
[<ffffffff85ce85d6>] vlan_newlink+0x3ca/0x5fa net/8021q/vlan_netlink.c:191
[<ffffffff84f5977a>] rtnl_newlink_create net/core/rtnetlink.c:3795 [inline]
[<ffffffff84f5977a>] __rtnl_newlink net/core/rtnetlink.c:3906 [inline]
[<ffffffff84f5977a>] rtnl_newlink+0xbb4/0x1acc net/core/rtnetlink.c:4021
[<ffffffff84f5c4aa>] rtnetlink_rcv_msg+0x9e2/0xdbe net/core/rtnetlink.c:6911
[<ffffffff852a21dc>] netlink_rcv_skb+0x216/0x3dc net/netlink/af_netlink.c:2543
[<ffffffff84f4a1f0>] rtnetlink_rcv+0x26/0x30 net/core/rtnetlink.c:6938
[<ffffffff852a0490>] netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline]
[<ffffffff852a0490>] netlink_unicast+0x4f0/0x82c net/netlink/af_netlink.c:1348
[<ffffffff852a1030>] netlink_sendmsg+0x864/0xdc6 net/netlink/af_netlink.c:1892
[<ffffffff84e3f9e2>] sock_sendmsg_nosec net/socket.c:713 [inline]
[<ffffffff84e3f9e2>] __sock_sendmsg+0xcc/0x160 net/socket.c:728
[<ffffffff84e405ee>] ____sys_sendmsg+0x5ce/0x79e net/socket.c:2568
[<ffffffff84e49160>] ___sys_sendmsg+0x144/0x1e6 net/socket.c:2622
[<ffffffff84e49f16>] __sys_sendmsg+0x188/0x22a net/socket.c:2654
[<ffffffff84e4a028>] __do_sys_sendmsg net/socket.c:2659 [inline]
[<ffffffff84e4a028>] __se_sys_sendmsg net/socket.c:2657 [inline]
[<ffffffff84e4a028>] __riscv_sys_sendmsg+0x70/0xa2 net/socket.c:2657
[<ffffffff80070b2c>] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:90
[<ffffffff861aecda>] do_trap_ecall_u+0x1aa/0x216 arch/riscv/kernel/traps.c:331
[<ffffffff861d41ea>] handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197

The buggy address belongs to the variable:
 vlan_mrp_app+0x60/0x3e80

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x89a04
flags: 0xffe000000002000(reserved|node=0|zone=0|lastcpupid=0x7ff)
raw: 0ffe000000002000 ff1c000000268108 ff1c000000268108 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffffffff89804a80: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff89804b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff89804b80: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
                   ^
 ffffffff89804c00: 00 00 00 00 00 00 00 00 f9 f9 f9 f9 00 00 00 00
 ffffffff89804c80: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
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