WARNING in kfree (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 2c523b34 Linux 5.6-rc5
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=154b5181e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=c2e311dba9a02ba9
dashboard link: https://syzkaller.appspot.com/bug?extid=50ef5e5e5ea5f812f0c2
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15d8ae91e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+50ef5e...@syzkaller.appspotmail.com

------------[ cut here ]------------
virt_to_cache: Object is not a Slab page!
WARNING: CPU: 1 PID: 9436 at mm/slab.h:473 virt_to_cache mm/slab.h:473 [inline]
WARNING: CPU: 1 PID: 9436 at mm/slab.h:473 kfree+0x1cf/0x2b0 mm/slab.c:3749
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 9436 Comm: syz-executor.0 Not tainted 5.6.0-rc5-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+0x188/0x20d lib/dump_stack.c:118
panic+0x2e3/0x75c kernel/panic.c:221
__warn.cold+0x2f/0x35 kernel/panic.c:582
report_bug+0x27b/0x2f0 lib/bug.c:195
fixup_bug arch/x86/kernel/traps.c:174 [inline]
fixup_bug arch/x86/kernel/traps.c:169 [inline]
do_error_trap+0x12b/0x220 arch/x86/kernel/traps.c:267
do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286
invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027
RIP: 0010:virt_to_cache mm/slab.h:473 [inline]
RIP: 0010:kfree+0x1cf/0x2b0 mm/slab.c:3749
Code: 51 ff e9 67 fe ff ff 80 3d 8a a4 b2 08 00 75 1c 48 c7 c6 40 52 15 88 48 c7 c7 e8 03 26 89 c6 05 73 a4 b2 08 01 e8 b9 9f 95 ff <0f> 0b f6 c7 02 75 6b 48 83 3d 52 2e c5 07 00 0f 85 4e ff ff ff 0f
RSP: 0018:ffffc900020e7030 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000282 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff815bf4f1 RDI: fffff5200041cdf8
RBP: ffffffff8c3f7080 R08: ffff88808e97c600 R09: ffffed1015ce45c9
R10: ffffed1015ce45c8 R11: ffff8880ae722e43 R12: ffffffff8628c202
R13: dffffc0000000000 R14: ffff8880a0069c10 R15: 0000000000000000
tcf_exts_destroy+0x62/0xc0 net/sched/cls_api.c:3002
tcf_exts_change+0xf4/0x150 net/sched/cls_api.c:3059
tcindex_set_parms+0xed8/0x1a00 net/sched/cls_tcindex.c:456
tcindex_change+0x203/0x2e0 net/sched/cls_tcindex.c:518
tc_new_tfilter+0xa59/0x20b0 net/sched/cls_api.c:2103
rtnetlink_rcv_msg+0x810/0xad0 net/core/rtnetlink.c:5427
netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2478
netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:672
____sys_sendmsg+0x6b9/0x7d0 net/socket.c:2343
___sys_sendmsg+0x100/0x170 net/socket.c:2397
__sys_sendmsg+0xec/0x1b0 net/socket.c:2430
do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline]
do_fast_syscall_32+0x270/0xe8f arch/x86/entry/common.c:408
entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
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syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

[syzbot]

syzbot has bisected this bug to:

commit 599be01ee567b61f4471ee8078870847d0a11e8e
Author: Cong Wang <xiyou.w...@gmail.com>
Date: Mon Feb 3 05:14:35 2020 +0000

net_sched: fix an OOB access in cls_tcindex

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=13257803e00000
start commit: 2c523b34 Linux 5.6-rc5
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=10a57803e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=17257803e00000

kernel config: https://syzkaller.appspot.com/x/.config?x=c2e311dba9a02ba9
dashboard link: https://syzkaller.appspot.com/bug?extid=50ef5e5e5ea5f812f0c2

userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15d8ae91e00000

Reported-by: syzbot+50ef5e...@syzkaller.appspotmail.com
Fixes: 599be01ee567 ("net_sched: fix an OOB access in cls_tcindex")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[syzbot]

syzbot suspects this bug was fixed by commit:

commit 0d1c3530e1bd38382edef72591b78e877e0edcd3
Author: Cong Wang <xiyou.w...@gmail.com>
Date: Thu Mar 12 05:42:28 2020 +0000

net_sched: keep alloc_hash updated after hash allocation

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1640e277e00000
start commit: 2c523b34 Linux 5.6-rc5
git tree: upstream

kernel config: https://syzkaller.appspot.com/x/.config?x=c2e311dba9a02ba9
dashboard link: https://syzkaller.appspot.com/bug?extid=50ef5e5e5ea5f812f0c2

userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15d8ae91e00000

If the result looks correct, please mark the bug fixed by replying with:

#syz fix: net_sched: keep alloc_hash updated after hash allocation

[Eric Biggers]