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SubjectKASAN: use-after-free Read in tcf_action_init
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Hello,

syzbot found the following issue on:

HEAD commit: 171d4ff7 Merge tag 'mmc-v5.9-rc4-2' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=105fbac5900000
kernel config: https://syzkaller.appspot.com/x/.config?x=af502ec9a451c9fc
dashboard link: https://syzkaller.appspot.com/bug?extid=9f43bb6a66ff96a21931
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13cb8f8b900000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12af2c81900000

The issue was bisected to:

commit 974e6f02e27e1b46c6c5e600e70ced25079f73eb
Author: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Date: Mon Aug 1 09:54:35 2016 +0000

iio: cros_ec_sensors_core: Add common functions for the ChromeOS EC Sensor Hub.

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11fe49d3900000
final oops: https://syzkaller.appspot.com/x/report.txt?x=13fe49d3900000
console output: https://syzkaller.appspot.com/x/log.txt?x=15fe49d3900000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9f43bb6a66ff96a21931@syzkaller.appspotmail.com
Fixes: 974e6f02e27e ("iio: cros_ec_sensors_core: Add common functions for the ChromeOS EC Sensor Hub.")

netlink: 32 bytes leftover after parsing attributes in process `syz-executor211'.
==================================================================
BUG: KASAN: use-after-free in tcf_action_destroy net/sched/act_api.c:724 [inline]
BUG: KASAN: use-after-free in tcf_action_init+0x231/0x3d0 net/sched/act_api.c:1058
Read of size 8 at addr ffff888097225c00 by task syz-executor211/7086

CPU: 0 PID: 7086 Comm: syz-executor211 Not tainted 5.9.0-rc6-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+0x1d6/0x29e lib/dump_stack.c:118
print_address_description+0x66/0x620 mm/kasan/report.c:383
__kasan_report mm/kasan/report.c:513 [inline]
kasan_report+0x132/0x1d0 mm/kasan/report.c:530
tcf_action_destroy net/sched/act_api.c:724 [inline]
tcf_action_init+0x231/0x3d0 net/sched/act_api.c:1058
tcf_action_add net/sched/act_api.c:1451 [inline]
tc_ctl_action+0x2c7/0x7e0 net/sched/act_api.c:1504
rtnetlink_rcv_msg+0x889/0xd40 net/core/rtnetlink.c:5563
netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2470
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1330
netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg net/socket.c:671 [inline]
____sys_sendmsg+0x519/0x800 net/socket.c:2353
___sys_sendmsg net/socket.c:2407 [inline]
__sys_sendmsg+0x2b1/0x360 net/socket.c:2440
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x44abe9
Code: e8 dc 13 03 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 0f 83 cb 0b fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f842a305ce8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000006e0c48 RCX: 000000000044abe9
RDX: 0000000000000000 RSI: 0000000020002980 RDI: 0000000000000003
RBP: 00000000006e0c40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006e0c4c
R13: 00007ffcf73121ef R14: 00007f842a3069c0 R15: 00000000006e0c4c

Allocated by task 7086:
kasan_save_stack mm/kasan/common.c:48 [inline]
kasan_set_track mm/kasan/common.c:56 [inline]
__kasan_kmalloc+0x100/0x130 mm/kasan/common.c:461
__do_kmalloc mm/slab.c:3655 [inline]
__kmalloc+0x205/0x300 mm/slab.c:3664
kmalloc include/linux/slab.h:559 [inline]
kzalloc+0x16/0x30 include/linux/slab.h:666
tcf_idr_create+0x56/0x5e0 net/sched/act_api.c:408
tcf_connmark_init+0x230/0x7d0 net/sched/act_connmark.c:126
tcf_action_init_1+0x7dc/0xce0 net/sched/act_api.c:984
tcf_action_init+0x114/0x3d0 net/sched/act_api.c:1043
tcf_action_add net/sched/act_api.c:1451 [inline]
tc_ctl_action+0x2c7/0x7e0 net/sched/act_api.c:1504
rtnetlink_rcv_msg+0x889/0xd40 net/core/rtnetlink.c:5563
netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2470
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1330
netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg net/socket.c:671 [inline]
____sys_sendmsg+0x519/0x800 net/socket.c:2353
___sys_sendmsg net/socket.c:2407 [inline]
__sys_sendmsg+0x2b1/0x360 net/socket.c:2440
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 7088:
kasan_save_stack mm/kasan/common.c:48 [inline]
kasan_set_track+0x3d/0x70 mm/kasan/common.c:56
kasan_set_free_info+0x17/0x30 mm/kasan/generic.c:355
__kasan_slab_free+0xdd/0x110 mm/kasan/common.c:422
__cache_free mm/slab.c:3418 [inline]
kfree+0x113/0x200 mm/slab.c:3756
tcf_idr_release_unsafe net/sched/act_api.c:284 [inline]
tcf_del_walker net/sched/act_api.c:310 [inline]
tcf_generic_walker+0x6f8/0xbc0 net/sched/act_api.c:339
tca_action_flush net/sched/act_api.c:1278 [inline]
tca_action_gd+0x135a/0x18f0 net/sched/act_api.c:1385
tc_ctl_action+0x395/0x7e0 net/sched/act_api.c:1512
rtnetlink_rcv_msg+0x889/0xd40 net/core/rtnetlink.c:5563
netlink_rcv_skb+0x190/0x3a0 net/netlink/af_netlink.c:2470
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x786/0x940 net/netlink/af_netlink.c:1330
netlink_sendmsg+0xa57/0xd70 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg net/socket.c:671 [inline]
____sys_sendmsg+0x519/0x800 net/socket.c:2353
___sys_sendmsg net/socket.c:2407 [inline]
__sys_sendmsg+0x2b1/0x360 net/socket.c:2440
do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888097225c00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 0 bytes inside of
512-byte region [ffff888097225c00, ffff888097225e00)
The buggy address belongs to the page:
page:00000000598892c8 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x97225
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea00028423c8 ffffea00028bbc48 ffff8880aa440600
raw: 0000000000000000 ffff888097225000 0000000100000004 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888097225b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888097225b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888097225c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888097225c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888097225d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches

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