KASAN: use-after-free Read in macvlan_dev_get_iflink

From: syzbot
Date: Sat Jun 27 2020 - 22:47:27 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 1590a2e1 Merge tag 'acpi-5.8-rc3' of git://git.kernel.org/..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1070059b100000
kernel config: https://syzkaller.appspot.com/x/.config?x=20c907630cbdbe5
dashboard link: https://syzkaller.appspot.com/bug?extid=95eec132c4bd9b1d8430
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1559e6e5100000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16aadd29100000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+95eec132c4bd9b1d8430@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in macvlan_dev_get_iflink+0x6a/0x70 drivers/net/macvlan.c:1137
Read of size 4 at addr ffff88808b62a100 by task syz-executor984/7033

CPU: 0 PID: 7033 Comm: syz-executor984 Not tainted 5.8.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1f0/0x31e lib/dump_stack.c:118
print_address_description+0x66/0x5a0 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report+0x132/0x1d0 mm/kasan/report.c:530
macvlan_dev_get_iflink+0x6a/0x70 drivers/net/macvlan.c:1137
default_operstate net/core/link_watch.c:41 [inline]
rfc2863_policy+0x11f/0x2a0 net/core/link_watch.c:53
linkwatch_do_dev+0x3a/0x160 net/core/link_watch.c:160
netdev_wait_allrefs net/core/dev.c:9678 [inline]
netdev_run_todo+0x2c8/0xc90 net/core/dev.c:9774
rtnl_unlock net/core/rtnetlink.c:112 [inline]
rtnetlink_rcv_msg+0x890/0xd40 net/core/rtnetlink.c:5461
netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2469
netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1329
netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg net/socket.c:672 [inline]
____sys_sendmsg+0x519/0x800 net/socket.c:2352
___sys_sendmsg net/socket.c:2406 [inline]
__sys_sendmsg+0x2b1/0x360 net/socket.c:2439
do_syscall_64+0x73/0xe0 arch/x86/entry/common.c:359
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x446e69
Code: Bad RIP value.
RSP: 002b:00007f7fa3a46d98 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000006dbc98 RCX: 0000000000446e69
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000006
RBP: 00000000006dbc90 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000000a R11: 0000000000000246 R12: 00000000006dbc9c
R13: 0000000000000000 R14: 0000000000000000 R15: 0705001000000048

Allocated by task 7001:
save_stack mm/kasan/common.c:48 [inline]
set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc+0x103/0x140 mm/kasan/common.c:494
kmalloc_node include/linux/slab.h:578 [inline]
kvmalloc_node+0x81/0x110 mm/util.c:574
kvmalloc include/linux/mm.h:753 [inline]
kvzalloc include/linux/mm.h:761 [inline]
alloc_netdev_mqs+0x86/0xf90 net/core/dev.c:9938
rtnl_create_link+0x242/0x9c0 net/core/rtnetlink.c:3067
__rtnl_newlink net/core/rtnetlink.c:3329 [inline]
rtnl_newlink+0x12a2/0x1bf0 net/core/rtnetlink.c:3397
rtnetlink_rcv_msg+0x889/0xd40 net/core/rtnetlink.c:5460
netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2469
netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1329
netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg net/socket.c:672 [inline]
____sys_sendmsg+0x519/0x800 net/socket.c:2352
___sys_sendmsg net/socket.c:2406 [inline]
__sys_sendmsg+0x2b1/0x360 net/socket.c:2439
do_syscall_64+0x73/0xe0 arch/x86/entry/common.c:359
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 7001:
save_stack mm/kasan/common.c:48 [inline]
set_track mm/kasan/common.c:56 [inline]
kasan_set_free_info mm/kasan/common.c:316 [inline]
__kasan_slab_free+0x114/0x170 mm/kasan/common.c:455
__cache_free mm/slab.c:3426 [inline]
kfree+0x10a/0x220 mm/slab.c:3757
device_release+0x70/0x1a0 drivers/base/core.c:1555
kobject_cleanup lib/kobject.c:693 [inline]
kobject_release lib/kobject.c:722 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x15b/0x220 lib/kobject.c:739
netdev_run_todo+0xb17/0xc90 net/core/dev.c:9797
rtnl_unlock net/core/rtnetlink.c:112 [inline]
rtnetlink_rcv_msg+0x890/0xd40 net/core/rtnetlink.c:5461
netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2469
netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1329
netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg net/socket.c:672 [inline]
____sys_sendmsg+0x519/0x800 net/socket.c:2352
___sys_sendmsg net/socket.c:2406 [inline]
__sys_sendmsg+0x2b1/0x360 net/socket.c:2439
do_syscall_64+0x73/0xe0 arch/x86/entry/common.c:359
entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff88808b62a000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 256 bytes inside of
4096-byte region [ffff88808b62a000, ffff88808b62b000)
The buggy address belongs to the page:
page:ffffea00022d8a80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea00022d8a80 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0002a12288 ffffea0002462c08 ffff8880aa402000
raw: 0000000000000000 ffff88808b62a000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88808b62a000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88808b62a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88808b62a100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88808b62a180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88808b62a200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
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Next message: Boris Ostrovsky: "Re: [PATCH 3/6] x86/entry/64/compat: Fix Xen PV SYSENTER frame setup"
Previous message: Bart Van Assche: "Re: [PATCH] scsi: sd: add runtime pm to open / release"
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