[v6.1] KASAN: use-after-free Read in gc_worker

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7dc732d24ff7 Linux 6.1.123
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1133f1c4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=da1827eaa51b65c3
dashboard link: https://syzkaller.appspot.com/bug?extid=43322bea177c120da32f
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b77a36eba7b4/disk-7dc732d2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f5334562da28/vmlinux-7dc732d2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f0a16f9a500c/Image-7dc732d2.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+43322b...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in gc_worker+0x5f8/0x125c
Read of size 8 at addr ffff0000f309d050 by task kworker/u4:13/4561

CPU: 1 PID: 4561 Comm: kworker/u4:13 Not tainted 6.1.123-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: events_power_efficient gc_worker
Call trace:
dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:316 [inline]
print_report+0x174/0x4c0 mm/kasan/report.c:427
kasan_report+0xd4/0x130 mm/kasan/report.c:531
__asan_report_load8_noabort+0x2c/0x38 mm/kasan/report_generic.c:351
gc_worker+0x5f8/0x125c
process_one_work+0x7ac/0x1404 kernel/workqueue.c:2292
worker_thread+0x8e4/0xfec kernel/workqueue.c:2439
kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:864

Allocated by task 8421:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4c/0x80 mm/kasan/common.c:52
kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:211 [inline]
kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031
kmalloc include/linux/slab.h:563 [inline]
kzalloc include/linux/slab.h:699 [inline]
nf_ct_tmpl_alloc+0x90/0x1f4 net/netfilter/nf_conntrack_core.c:550
nft_ct_set_zone_eval+0x3c8/0x600 net/netfilter/nft_ct.c:270
expr_call_ops_eval net/netfilter/nf_tables_core.c:214 [inline]
nft_do_chain+0x440/0x1544 net/netfilter/nf_tables_core.c:264
nft_do_chain_ipv4+0x1a4/0x2d8 net/netfilter/nft_chain_filter.c:23
nf_hook_entry_hookfn include/linux/netfilter.h:142 [inline]
nf_hook_slow+0xc8/0x1f4 net/netfilter/core.c:614
nf_hook include/linux/netfilter.h:257 [inline]
NF_HOOK+0x22c/0x3d4 include/linux/netfilter.h:300
ip_rcv+0x78/0x98 net/ipv4/ip_input.c:569
__netif_receive_skb_one_core net/core/dev.c:5536 [inline]
__netif_receive_skb+0x18c/0x400 net/core/dev.c:5650
process_backlog+0x410/0x784 net/core/dev.c:5978
__napi_poll+0xb4/0x3f0 net/core/dev.c:6545
napi_poll net/core/dev.c:6612 [inline]
net_rx_action+0x5cc/0xd3c net/core/dev.c:6726
handle_softirqs+0x318/0xd58 kernel/softirq.c:571
__do_softirq+0x14/0x20 kernel/softirq.c:605

Freed by task 4561:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4c/0x80 mm/kasan/common.c:52
kasan_save_free_info+0x38/0x5c mm/kasan/generic.c:516
____kasan_slab_free+0x144/0x1c0 mm/kasan/common.c:236
__kasan_slab_free+0x18/0x28 mm/kasan/common.c:244
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1724 [inline]
slab_free_freelist_hook mm/slub.c:1750 [inline]
slab_free mm/slub.c:3661 [inline]
__kmem_cache_free+0x2c0/0x4b4 mm/slub.c:3674
kfree+0xcc/0x1b8 mm/slab_common.c:988
nf_ct_tmpl_free net/netfilter/nf_conntrack_core.c:571 [inline]
nf_ct_destroy+0x198/0x298 net/netfilter/nf_conntrack_core.c:593
nf_ct_put include/net/netfilter/nf_conntrack.h:190 [inline]
nf_ct_gc_expired+0x2dc/0x424 net/netfilter/nf_conntrack_core.c:739
gc_worker+0x550/0x125c net/netfilter/nf_conntrack_core.c:1536
process_one_work+0x7ac/0x1404 kernel/workqueue.c:2292
worker_thread+0x8e4/0xfec kernel/workqueue.c:2439
kthread+0x250/0x2d8 kernel/kthread.c:376
ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:864

The buggy address belongs to the object at ffff0000f309d000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 80 bytes inside of
512-byte region [ffff0000f309d000, ffff0000f309d200)

The buggy address belongs to the physical page:
page:00000000e05b3caf refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff0000f309fc00 pfn:0x13309c
head:00000000e05b3caf order:2 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 fffffc0003c3c508 fffffc0003324208 ffff0000c0002600
raw: ffff0000f309fc00 000000000010000f 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff0000f309cf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff0000f309cf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000f309d000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff0000f309d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff0000f309d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.