KASAN: use-after-free Read in ipvlan_queue_xmit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 27ce4f2a Linux 4.14.206
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17d6a3ba500000
kernel config: https://syzkaller.appspot.com/x/.config?x=32258a0e1fac372d
dashboard link: https://syzkaller.appspot.com/bug?extid=7c0ed21eeb1e307756cc
compiler: gcc (GCC) 10.1.0-syz 20200507
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=139f64a6500000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16dc5572500000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7c0ed2...@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_CHANGE): macvtap0: link becomes ready
batman_adv: batadv0: Interface activated: batadv_slave_1
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): ipvlan1: link is not ready
==================================================================
BUG: KASAN: use-after-free in ether_addr_equal include/linux/etherdevice.h:321 [inline]
BUG: KASAN: use-after-free in ipvlan_xmit_mode_l2 drivers/net/ipvlan/ipvlan_core.c:542 [inline]
BUG: KASAN: use-after-free in ipvlan_queue_xmit+0x1323/0x15a0 drivers/net/ipvlan/ipvlan_core.c:583
Read of size 4 at addr ffff88809f62453f by task syz-executor996/8001
IPv6: ADDRCONF(NETDEV_CHANGE): bond0: link becomes ready

CPU: 1 PID: 8001 Comm: syz-executor996 Not tainted 4.14.206-syzkaller #0
IPv6: ADDRCONF(NETDEV_CHANGE): ipvlan1: link becomes ready
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x283 lib/dump_stack.c:58
print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
kasan_report mm/kasan/report.c:409 [inline]
__asan_report_load4_noabort+0x68/0x70 mm/kasan/report.c:429
ether_addr_equal include/linux/etherdevice.h:321 [inline]
ipvlan_xmit_mode_l2 drivers/net/ipvlan/ipvlan_core.c:542 [inline]
ipvlan_queue_xmit+0x1323/0x15a0 drivers/net/ipvlan/ipvlan_core.c:583
ipvlan_start_xmit+0x4f/0x180 drivers/net/ipvlan/ipvlan_main.c:286
__netdev_start_xmit include/linux/netdevice.h:4039 [inline]
netdev_start_xmit include/linux/netdevice.h:4048 [inline]
packet_direct_xmit+0x410/0x610 net/packet/af_packet.c:269
packet_snd+0x1393/0x21e0 net/packet/af_packet.c:3024
packet_sendmsg+0x1139/0x2aca net/packet/af_packet.c:3049
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xb5/0x100 net/socket.c:656
SYSC_sendto net/socket.c:1763 [inline]
SyS_sendto+0x1c7/0x2c0 net/socket.c:1731
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x444a29
RSP: 002b:00007ffc76122098 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000444a29
RDX: 000000000000000e RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00007ffc761220c0 R08: 0000000000000000 R09: ffffffffffffff09
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffc761220d0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 1:
save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
kmem_cache_alloc+0x124/0x3c0 mm/slab.c:3552
getname_flags+0xc8/0x550 fs/namei.c:138
user_path_at_empty+0x2a/0x50 fs/namei.c:2631
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0xd1/0x180 fs/stat.c:185
vfs_lstat include/linux/fs.h:3070 [inline]
SYSC_newlstat fs/stat.c:350 [inline]
SyS_newlstat+0x83/0xe0 fs/stat.c:344
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 1:
save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kmem_cache_free+0x7c/0x2b0 mm/slab.c:3758
putname+0xcd/0x110 fs/namei.c:259
filename_lookup+0x37b/0x510 fs/namei.c:2386
user_path_at include/linux/namei.h:57 [inline]
vfs_statx+0xd1/0x180 fs/stat.c:185
vfs_lstat include/linux/fs.h:3070 [inline]
SYSC_newlstat fs/stat.c:350 [inline]
SyS_newlstat+0x83/0xe0 fs/stat.c:344
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff88809f624440
which belongs to the cache names_cache of size 4096
The buggy address is located 255 bytes inside of
4096-byte region [ffff88809f624440, ffff88809f625440)
The buggy address belongs to the page:
page:ffffea00027d8900 count:1 mapcount:0 mapping:ffff88809f624440 index:0x0 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffff88809f624440 0000000000000000 0000000100000001
raw: ffffea00027d2720 ffffea00027c19a0 ffff88823f8bb200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88809f624400: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff88809f624480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88809f624500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88809f624580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88809f624600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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