syzbot


WARNING: refcount bug in xp_put_pool

Status: fixed on 2023/10/12 12:48
Subsystems: bpf net
[Documentation on labels]
Reported-by: syzbot+8ada0057e69293a05fd4@syzkaller.appspotmail.com
Fix commit: 85c2c79a0730 xsk: fix refcount underflow in error path
First crash: 301d, last: 301d
Cause bisection: introduced by (bisect log) :
commit 9f78bf330a66cd400b3e00f370f597e9fa939207
Author: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Date: Thu Feb 16 08:30:47 2023 +0000

  xsk: support use vaddr as ring

Crash: WARNING: refcount bug in xp_put_pool (log)
Repro: C syz .config
  
Discussions (2)
Title Replies (including bot) Last reply
[PATCH bpf] xsk: fix refcount underflow in error path 2 (2) 2023/08/10 03:30
[syzbot] [bpf?] [net?] WARNING: refcount bug in xp_put_pool 0 (1) 2023/07/31 07:57
Last patch testing requests (2)
Created Duration User Patch Repo Result
2023/08/09 10:38 47m magnus.karlsson@intel.com patch https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git 999f6631866e9ea81add935b9c6ebaab0579d259 OK log
2023/07/31 11:01 24m hdanton@sina.com patch https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git d7b3af5a77e8 OK log

Sample crash report:
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 5078 at lib/refcount.c:28 refcount_warn_saturate+0x140/0x1f0 lib/refcount.c:28
Modules linked in:
CPU: 0 PID: 5078 Comm: kworker/0:3 Not tainted 6.5.0-rc3-next-20230728-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Workqueue: events drain_vmap_area_work
RIP: 0010:refcount_warn_saturate+0x140/0x1f0 lib/refcount.c:28
Code: 0a 31 ff 89 de e8 f0 3e 65 fd 84 db 0f 85 6e ff ff ff e8 b3 43 65 fd 48 c7 c7 c0 33 c8 8a c6 05 64 ce 74 0a 01 e8 60 99 2b fd <0f> 0b e9 4f ff ff ff e8 94 43 65 fd 0f b6 1d 4a ce 74 0a 31 ff 89
RSP: 0018:ffffc90000007d88 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000100
RDX: ffff88807190d940 RSI: ffffffff814d5b56 RDI: 0000000000000001
RBP: ffff888071110460 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: ffff888071110460
R13: ffff8880710d24e8 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555557361650 CR3: 00000000476b6000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __refcount_sub_and_test include/linux/refcount.h:283 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 xp_put_pool+0x8a/0x1e0 net/xdp/xsk_buff_pool.c:286
 xsk_destruct+0x95/0x140 net/xdp/xsk.c:1601
 __sk_destruct+0x4d/0x770 net/core/sock.c:2163
 rcu_do_batch kernel/rcu/tree.c:2139 [inline]
 rcu_core+0x7fb/0x1bb0 kernel/rcu/tree.c:2403
 __do_softirq+0x218/0x965 kernel/softirq.c:553
 invoke_softirq kernel/softirq.c:427 [inline]
 __irq_exit_rcu kernel/softirq.c:632 [inline]
 irq_exit_rcu+0xb7/0x120 kernel/softirq.c:644
 common_interrupt+0xae/0xd0 arch/x86/kernel/irq.c:247
 </IRQ>
 <TASK>
 asm_common_interrupt+0x26/0x40 arch/x86/include/asm/idtentry.h:636
RIP: 0010:stack_trace_consume_entry+0xaf/0x160 kernel/stacktrace.c:93
Code: c0 03 38 d0 7c 08 84 d2 0f 85 90 00 00 00 8b 43 0c 85 c0 75 53 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 80 3c 02 00 <0f> 85 92 00 00 00 8d 45 01 89 43 10 48 8b 03 48 8d 2c e8 48 b8 00
RSP: 0018:ffffc90003d7f6d8 EFLAGS: 00000246
RAX: dffffc0000000000 RBX: ffffc90003d7f7b8 RCX: 0000000000000000
RDX: 1ffff920007afef7 RSI: ffffffff81cffbd8 RDI: ffffc90003d7f7c4
RBP: 0000000000000000 R08: ffffc90003d7f72c R09: ffffffff8f40e62e
R10: ffffc90003d7f6f8 R11: 000000000000e4d6 R12: ffffffff8174c470
R13: ffffc90003d7f7b8 R14: 0000000000000000 R15: ffff88807190d940
 arch_stack_walk+0x7f/0xf0 arch/x86/kernel/stacktrace.c:27
 stack_trace_save+0x96/0xd0 kernel/stacktrace.c:122
 save_stack+0x160/0x1f0 mm/page_owner.c:128
 __reset_page_owner+0x5a/0x190 mm/page_owner.c:149
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1160 [inline]
 free_unref_page_prepare+0x508/0xb90 mm/page_alloc.c:2383
 free_unref_page+0x33/0x3b0 mm/page_alloc.c:2478
 kasan_depopulate_vmalloc_pte+0x63/0x80 mm/kasan/shadow.c:427
 apply_to_pte_range mm/memory.c:2735 [inline]
 apply_to_pmd_range mm/memory.c:2779 [inline]
 apply_to_pud_range mm/memory.c:2815 [inline]
 apply_to_p4d_range mm/memory.c:2851 [inline]
 __apply_to_page_range+0x5ed/0xdb0 mm/memory.c:2885
 kasan_release_vmalloc+0xa8/0xc0 mm/kasan/shadow.c:544
 __purge_vmap_area_lazy+0x8b9/0x2160 mm/vmalloc.c:1770
 drain_vmap_area_work+0x54/0xd0 mm/vmalloc.c:1804
 process_one_work+0xaa2/0x16f0 kernel/workqueue.c:2603
 worker_thread+0x687/0x1110 kernel/workqueue.c:2754
 kthread+0x33a/0x430 kernel/kthread.c:389
 ret_from_fork+0x2c/0x70 arch/x86/kernel/process.c:145
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	38 d0                	cmp    %dl,%al
   2:	7c 08                	jl     0xc
   4:	84 d2                	test   %dl,%dl
   6:	0f 85 90 00 00 00    	jne    0x9c
   c:	8b 43 0c             	mov    0xc(%rbx),%eax
   f:	85 c0                	test   %eax,%eax
  11:	75 53                	jne    0x66
  13:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  1a:	fc ff df
  1d:	48 89 da             	mov    %rbx,%rdx
  20:	48 c1 ea 03          	shr    $0x3,%rdx
  24:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
* 28:	0f 85 92 00 00 00    	jne    0xc0 <-- trapping instruction
  2e:	8d 45 01             	lea    0x1(%rbp),%eax
  31:	89 43 10             	mov    %eax,0x10(%rbx)
  34:	48 8b 03             	mov    (%rbx),%rax
  37:	48 8d 2c e8          	lea    (%rax,%rbp,8),%rbp
  3b:	48                   	rex.W
  3c:	b8                   	.byte 0xb8

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/07/29 12:59 linux-next d7b3af5a77e8 92476829 .config strace log report syz C [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING: refcount bug in xp_put_pool
2023/07/29 11:02 linux-next d7b3af5a77e8 92476829 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root WARNING: refcount bug in xp_put_pool
* Struck through repros no longer work on HEAD.