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BUG: KASAN: global-out-of-bounds in memcmp+0xc0/0xca lib/string.c:676
Read of size 1 at addr ffffffff897cc9c0 by task syz.1.685/9921

CPU: 0 UID: 0 PID: 9921 Comm: syz.1.685 Not tainted 6.12.0-rc6-syzkaller-g57f7c7dc78cd #0
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
[<ffffffff80010a0c>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:130
[<ffffffff85f822a0>] show_stack+0x34/0x40 arch/riscv/kernel/stacktrace.c:136
[<ffffffff85fdd896>] __dump_stack lib/dump_stack.c:94 [inline]
[<ffffffff85fdd896>] dump_stack_lvl+0x122/0x196 lib/dump_stack.c:120
[<ffffffff85f8c0c4>] print_address_description mm/kasan/report.c:377 [inline]
[<ffffffff85f8c0c4>] print_report+0x290/0x5a0 mm/kasan/report.c:488
[<ffffffff809708ec>] kasan_report+0xec/0x118 mm/kasan/report.c:601
[<ffffffff8097271a>] __asan_report_load1_noabort+0x12/0x1a mm/kasan/report_generic.c:378
[<ffffffff85f58484>] memcmp+0xc0/0xca lib/string.c:676
[<ffffffff84d3c0dc>] __hw_addr_add_ex+0xee/0x676 net/core/dev_addr_lists.c:88
[<ffffffff84d3f0e8>] __dev_mc_add net/core/dev_addr_lists.c:867 [inline]
[<ffffffff84d3f0e8>] dev_mc_add+0xac/0x108 net/core/dev_addr_lists.c:885
[<ffffffff84ee0d9a>] mrp_init_applicant+0xe8/0x56e net/802/mrp.c:873
[<ffffffff85ad5e42>] vlan_mvrp_init_applicant+0x26/0x30 net/8021q/vlan_mvrp.c:57
[<ffffffff85acbef0>] register_vlan_dev+0x1b4/0x922 net/8021q/vlan.c:170
[<ffffffff85accbac>] register_vlan_device net/8021q/vlan.c:277 [inline]
[<ffffffff85accbac>] vlan_ioctl_handler+0x54e/0x956 net/8021q/vlan.c:621
[<ffffffff84c65ee2>] sock_ioctl+0x1f6/0x61a net/socket.c:1310
[<ffffffff80a76f18>] vfs_ioctl fs/ioctl.c:51 [inline]
[<ffffffff80a76f18>] __do_sys_ioctl fs/ioctl.c:907 [inline]
[<ffffffff80a76f18>] __se_sys_ioctl fs/ioctl.c:893 [inline]
[<ffffffff80a76f18>] __riscv_sys_ioctl+0x182/0x1e6 fs/ioctl.c:893
[<ffffffff8000f2cc>] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:90
[<ffffffff85fdfb66>] do_trap_ecall_u+0x1aa/0x216 arch/riscv/kernel/traps.c:331
[<ffffffff860029b6>] _new_vmalloc_restore_context_a0+0xc2/0xce

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:0x899cc
flags: 0xffe000000002000(reserved|node=0|zone=0|lastcpupid=0x7ff)
raw: 0ffe000000002000 ff1c000000267308 ff1c000000267308 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:
 ffffffff897cc880: 00 00 00 00 00 00 00 00 f9 f9 f9 f9 00 00 00 00
 ffffffff897cc900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff897cc980: 00 00 00 00 00 00 00 00 f9 f9 f9 f9 00 00 00 00
                                           ^
 ffffffff897cca00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff897cca80: f9 f9 f9 f9 00 00 00 00 f9 f9 f9 f9 00 00 00 00
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