KASAN: use-after-free Read in qfq_find_class

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13d7e82e080000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=cf679058a8708cf17d84
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cf6790...@syzkaller.appspotmail.com

nla_parse: 23 callbacks suppressed
netlink: 24 bytes leftover after parsing attributes in process `syz-executor.4'.
==================================================================
BUG: KASAN: use-after-free in qdisc_class_find include/net/sch_generic.h:528 [inline]
BUG: KASAN: use-after-free in qfq_find_class+0x162/0x190 net/sched/sch_qfq.c:214
Read of size 4 at addr ffff8880aa05d000 by task syz-executor.0/2105

CPU: 1 PID: 2105 Comm: syz-executor.0 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
kasan_report mm/kasan/report.c:412 [inline]
__asan_report_load4_noabort+0x88/0x90 mm/kasan/report.c:432
qdisc_class_find include/net/sch_generic.h:528 [inline]
qfq_find_class+0x162/0x190 net/sched/sch_qfq.c:214
tc_ctl_tclass+0x765/0xcd0 net/sched/sch_api.c:1957
rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227
__sys_sendmsg net/socket.c:2265 [inline]
__do_sys_sendmsg net/socket.c:2274 [inline]
__se_sys_sendmsg net/socket.c:2272 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2272
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f2117f31209
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f21168a6168 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f2118043f60 RCX: 00007f2117f31209
RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 0000000000000003
RBP: 00007f2117f8b161 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffcd13e304f R14: 00007f21168a6300 R15: 0000000000022000

Allocated by task 11359:
kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
qfq_change_class+0x885/0x16f0 net/sched/sch_qfq.c:476
tc_ctl_tclass+0x501/0xcd0 net/sched/sch_api.c:1993
rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227
__sys_sendmsg net/socket.c:2265 [inline]
__do_sys_sendmsg net/socket.c:2274 [inline]
__se_sys_sendmsg net/socket.c:2272 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2272
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 2089:
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
qfq_change_class+0x11ff/0x16f0 net/sched/sch_qfq.c:528
tc_ctl_tclass+0x501/0xcd0 net/sched/sch_api.c:1993
rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227
__sys_sendmsg net/socket.c:2265 [inline]
__do_sys_sendmsg net/socket.c:2274 [inline]
__se_sys_sendmsg net/socket.c:2272 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2272
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880aa05d000
which belongs to the cache kmalloc-128 of size 128
The buggy address is located 0 bytes inside of
128-byte region [ffff8880aa05d000, ffff8880aa05d080)
The buggy address belongs to the page:
page:ffffea0002a81740 count:1 mapcount:0 mapping:ffff88813bff0640 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea0002a38e48 ffffea0002d1f608 ffff88813bff0640
raw: 0000000000000000 ffff8880aa05d000 0000000100000015 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880aa05cf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff8880aa05cf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880aa05d000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880aa05d080: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
ffff8880aa05d100: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
==================================================================


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y

console output: https://syzkaller.appspot.com/x/log.txt?x=130b5cca080000

kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=cf679058a8708cf17d84
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12a4e0c1080000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1111357a080000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cf6790...@syzkaller.appspotmail.com

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000007
R13: 00000000000f4240 R14: 0000000000000000 R15: 0000000000000000
netlink: 24 bytes leftover after parsing attributes in process `syz-executor409'.
netlink: 72 bytes leftover after parsing attributes in process `syz-executor409'.

==================================================================
BUG: KASAN: use-after-free in qdisc_class_find include/net/sch_generic.h:528 [inline]
BUG: KASAN: use-after-free in qfq_find_class+0x162/0x190 net/sched/sch_qfq.c:214

Read of size 4 at addr ffff88809bbde480 by task syz-executor409/8308

CPU: 1 PID: 8308 Comm: syz-executor409 Not tainted 4.19.211-syzkaller #0

RIP: 0033:0x7fc456b90e69
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff2b505fe8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fff2b506020 RCX: 00007fc456b90e69
RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 00007fff2b506010
R13: 00000000000f4240 R14: 00000000000084d1 R15: 00007fff2b505ff4

Allocated by task 8303:

kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
qfq_change_class+0x885/0x16f0 net/sched/sch_qfq.c:476
tc_ctl_tclass+0x501/0xcd0 net/sched/sch_api.c:1993
rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227
__sys_sendmsg net/socket.c:2265 [inline]
__do_sys_sendmsg net/socket.c:2274 [inline]
__se_sys_sendmsg net/socket.c:2272 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2272
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 8303:

__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
qfq_change_class+0x11ff/0x16f0 net/sched/sch_qfq.c:528
tc_ctl_tclass+0x501/0xcd0 net/sched/sch_api.c:1993
rtnetlink_rcv_msg+0x453/0xb80 net/core/rtnetlink.c:4782
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227
__sys_sendmsg net/socket.c:2265 [inline]
__do_sys_sendmsg net/socket.c:2274 [inline]
__se_sys_sendmsg net/socket.c:2272 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2272
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809bbde480

which belongs to the cache kmalloc-128 of size 128
The buggy address is located 0 bytes inside of

128-byte region [ffff88809bbde480, ffff88809bbde500)

The buggy address belongs to the page:

page:ffffea00026ef780 count:1 mapcount:0 mapping:ffff88813bff0640 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea00026b1708 ffffea0002ccfc88 ffff88813bff0640
raw: 0000000000000000 ffff88809bbde000 0000000100000015 0000000000000000

page dumped because: kasan: bad access detected

Memory state around the buggy address:

ffff88809bbde380: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
ffff88809bbde400: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>ffff88809bbde480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88809bbde500: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
ffff88809bbde580: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================