From: syzbot ci <syzbot+ci3826af8b4f91bf97@syzkaller.appspotmail.com>
To: andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
daniel@iogearbox.net, eddyz87@gmail.com, kernel-team@meta.com,
kkd@meta.com, martin.lau@kernel.org, memxor@gmail.com,
paulmck@kernel.org, yatsenko@meta.com
Cc: syzbot@lists.linux.dev, syzkaller-bugs@googlegroups.com
Subject: [syzbot ci] Re: Close race in freeing special fields and map value
Date: Thu, 26 Feb 2026 01:31:53 -0800 [thread overview]
Message-ID: <69a01309.050a0220.2fcbed.0007.GAE@google.com> (raw)
In-Reply-To: <20260225185121.2057388-1-memxor@gmail.com>
syzbot ci has tested the following series
[v1] Close race in freeing special fields and map value
https://lore.kernel.org/all/20260225185121.2057388-1-memxor@gmail.com
* [PATCH bpf-next v1 1/4] bpf: Register dtor for freeing special fields
* [PATCH bpf-next v1 2/4] bpf: Delay freeing fields in local storage
* [PATCH bpf-next v1 3/4] bpf: Retire rcu_trace_implies_rcu_gp() from local storage
* [PATCH bpf-next v1 4/4] selftests/bpf: Add tests for special fields races
and found the following issue:
KASAN: slab-use-after-free Read in free_all
Full report is available here:
https://ci.syzbot.org/series/ad9c7ce6-d861-4afe-821a-e8fae6120b12
***
KASAN: slab-use-after-free Read in free_all
tree: bpf-next
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next.git
base: f620af11c27b8ec9994a39fe968aa778112d1566
arch: amd64
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config: https://ci.syzbot.org/builds/b2735b0b-963d-41a7-bb33-db10494a24e1/config
syz repro: https://ci.syzbot.org/findings/3ee61f99-7d80-4986-a0b1-492ffb6b1c46/syz_repro
==================================================================
BUG: KASAN: slab-use-after-free in free_all+0x84/0x140 kernel/bpf/memalloc.c:271
Read of size 8 at addr ffff888112ee9260 by task swapper/0/0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xba/0x230 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
free_all+0x84/0x140 kernel/bpf/memalloc.c:271
do_call_rcu_ttrace+0x385/0x400 kernel/bpf/memalloc.c:315
__free_by_rcu+0x23b/0x3f0 kernel/bpf/memalloc.c:381
rcu_do_batch kernel/rcu/tree.c:2617 [inline]
rcu_core+0x7cd/0x1070 kernel/rcu/tree.c:2869
handle_softirqs+0x22a/0x870 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723
irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:63
Code: 8e 6d 02 c3 cc cc cc cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 43 3d 1c 00 fb f4 <e9> 7c ea 02 00 cc cc cc cc cc cc cc cc cc cc cc cc 90 90 90 90 90
RSP: 0018:ffffffff8e407dc0 EFLAGS: 00000202
RAX: 00000000000d2297 RBX: ffffffff819a80ad RCX: 0000000080000001
RDX: 0000000000000001 RSI: ffffffff8def22fa RDI: ffffffff8c27a800
RBP: ffffffff8e407eb0 R08: ffff88812103395b R09: 1ffff1102420672b
R10: dffffc0000000000 R11: ffffed102420672c R12: ffffffff90117db0
R13: 1ffffffff1c929d8 R14: 0000000000000000 R15: 0000000000000000
arch_safe_halt arch/x86/kernel/process.c:766 [inline]
default_idle+0x9/0x20 arch/x86/kernel/process.c:767
default_idle_call+0x72/0xb0 kernel/sched/idle.c:122
cpuidle_idle_call kernel/sched/idle.c:191 [inline]
do_idle+0x1bd/0x500 kernel/sched/idle.c:332
cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:430
rest_init+0x2de/0x300 init/main.c:760
start_kernel+0x385/0x3d0 init/main.c:1210
x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
common_startup_64+0x13e/0x147
</TASK>
Allocated by task 5961:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__do_kmalloc_node mm/slub.c:5219 [inline]
__kmalloc_node_noprof+0x4e0/0x7c0 mm/slub.c:5225
kmalloc_node_noprof include/linux/slab.h:1093 [inline]
__bpf_map_area_alloc kernel/bpf/syscall.c:398 [inline]
bpf_map_area_alloc+0x64/0x170 kernel/bpf/syscall.c:411
trie_alloc+0x14f/0x340 kernel/bpf/lpm_trie.c:588
map_create+0xafd/0x16a0 kernel/bpf/syscall.c:1507
__sys_bpf+0x6e1/0x950 kernel/bpf/syscall.c:6210
__do_sys_bpf kernel/bpf/syscall.c:6341 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6339 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6339
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 83:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2687 [inline]
slab_free mm/slub.c:6124 [inline]
kfree+0x1c1/0x630 mm/slub.c:6442
bpf_map_free kernel/bpf/syscall.c:892 [inline]
bpf_map_free_deferred+0x217/0x460 kernel/bpf/syscall.c:919
process_one_work kernel/workqueue.c:3275 [inline]
process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
kthread+0x388/0x470 kernel/kthread.c:467
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
insert_work+0x3d/0x330 kernel/workqueue.c:2199
__queue_work+0xd03/0x1020 kernel/workqueue.c:2354
queue_work_on+0x106/0x1d0 kernel/workqueue.c:2405
bpf_map_put_with_uref kernel/bpf/syscall.c:975 [inline]
bpf_map_release+0x127/0x140 kernel/bpf/syscall.c:985
__fput+0x44f/0xa70 fs/file_table.c:469
task_work_run+0x1d9/0x270 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888112ee9000
which belongs to the cache kmalloc-cg-1k of size 1024
The buggy address is located 608 bytes inside of
freed 1024-byte region [ffff888112ee9000, ffff888112ee9400)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112ee8
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888106b17c01
flags: 0x17ff00000000040(head|node=0|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 017ff00000000040 ffff88810005d280 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 ffff888106b17c01
head: 017ff00000000040 ffff88810005d280 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 ffff888106b17c01
head: 017ff00000000003 ffffea00044bba01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5550, tgid 5550 (dhcpcd), ts 37867090520, free_ts 37834172120
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
prep_new_page mm/page_alloc.c:1897 [inline]
get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
alloc_slab_page mm/slub.c:3255 [inline]
allocate_slab+0x77/0x660 mm/slub.c:3444
new_slab mm/slub.c:3502 [inline]
refill_objects+0x331/0x3c0 mm/slub.c:7134
refill_sheaf mm/slub.c:2804 [inline]
__pcs_replace_empty_main+0x2b9/0x620 mm/slub.c:4578
alloc_from_pcs mm/slub.c:4681 [inline]
slab_alloc_node mm/slub.c:4815 [inline]
__do_kmalloc_node mm/slub.c:5218 [inline]
__kmalloc_node_track_caller_noprof+0x572/0x7b0 mm/slub.c:5327
kmalloc_reserve net/core/skbuff.c:635 [inline]
__alloc_skb+0x2c1/0x7d0 net/core/skbuff.c:713
alloc_skb include/linux/skbuff.h:1383 [inline]
alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6750
sock_alloc_send_pskb+0x878/0x990 net/core/sock.c:2995
unix_dgram_sendmsg+0x460/0x18e0 net/unix/af_unix.c:2125
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
sock_write_iter+0x503/0x550 net/socket.c:1195
do_iter_readv_writev+0x619/0x8c0 fs/read_write.c:-1
vfs_writev+0x33c/0x990 fs/read_write.c:1059
do_writev+0x154/0x2e0 fs/read_write.c:1105
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
page last free pid 5678 tgid 5678 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1433 [inline]
__free_frozen_pages+0xc2b/0xdb0 mm/page_alloc.c:2978
__slab_free+0x263/0x2b0 mm/slub.c:5532
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4501 [inline]
slab_alloc_node mm/slub.c:4830 [inline]
__do_kmalloc_node mm/slub.c:5218 [inline]
__kmalloc_noprof+0x316/0x760 mm/slub.c:5231
kmalloc_noprof include/linux/slab.h:966 [inline]
tomoyo_realpath_from_path+0xe3/0x5d0 security/tomoyo/realpath.c:251
tomoyo_realpath_nofollow+0xc3/0x110 security/tomoyo/realpath.c:304
tomoyo_find_next_domain+0x259/0x1aa0 security/tomoyo/domain.c:731
tomoyo_bprm_check_security+0x11b/0x180 security/tomoyo/tomoyo.c:102
security_bprm_check+0x85/0x240 security/security.c:794
search_binary_handler fs/exec.c:1654 [inline]
exec_binprm fs/exec.c:1696 [inline]
bprm_execve+0x896/0x1460 fs/exec.c:1748
do_execveat_common+0x50d/0x690 fs/exec.c:1846
__do_sys_execve fs/exec.c:1930 [inline]
__se_sys_execve fs/exec.c:1924 [inline]
__x64_sys_execve+0x97/0xc0 fs/exec.c:1924
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff888112ee9100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888112ee9180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888112ee9200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888112ee9280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888112ee9300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 8e 6d 02 mov 0x2(%rbp),%gs
3: c3 ret
4: cc int3
5: cc int3
6: cc int3
7: cc int3
8: cc int3
9: cc int3
a: cc int3
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: 90 nop
14: 90 nop
15: 90 nop
16: 90 nop
17: 90 nop
18: 90 nop
19: 90 nop
1a: 90 nop
1b: f3 0f 1e fa endbr64
1f: eb 07 jmp 0x28
21: 0f 00 2d 43 3d 1c 00 verw 0x1c3d43(%rip) # 0x1c3d6b
28: fb sti
29: f4 hlt
* 2a: e9 7c ea 02 00 jmp 0x2eaab <-- trapping instruction
2f: cc int3
30: cc int3
31: cc int3
32: cc int3
33: cc int3
34: cc int3
35: cc int3
36: cc int3
37: cc int3
38: cc int3
39: cc int3
3a: cc int3
3b: 90 nop
3c: 90 nop
3d: 90 nop
3e: 90 nop
3f: 90 nop
***
If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syzbot@syzkaller.appspotmail.com
---
This report is generated by a bot. It may contain errors.
syzbot ci engineers can be reached at syzkaller@googlegroups.com.
next parent reply other threads:[~2026-02-26 9:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20260225185121.2057388-1-memxor@gmail.com>
2026-02-26 9:31 ` syzbot ci [this message]
2026-02-26 15:05 ` [syzbot ci] Re: Close race in freeing special fields and map value Kumar Kartikeya Dwivedi
2026-02-26 17:36 ` Kumar Kartikeya Dwivedi
2026-02-26 17:38 ` syzbot ci
2026-02-26 18:28 ` Kumar Kartikeya Dwivedi
2026-02-26 18:30 ` syzbot ci
2026-02-26 18:36 ` [PATCH] please work syzbot Kumar Kartikeya Dwivedi
2026-02-26 18:42 ` syzbot ci
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