Re: [syzbot] [bpf?] [net?] KASAN: slab-use-after-free Read in bq_xmit_all

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in bq_flush_to_queue

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 6041 Comm: syz.0.49 Not tainted 6.10.0-syzkaller-11185-g2c9b3512402e-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
RIP: 0010:bq_flush_to_queue+0x44/0x610 kernel/bpf/cpumap.c:675
Code: df e8 30 d9 d6 ff 49 8d 5e 50 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 d6 cd 39 00 48 8b 2b 48 89 e8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 1d 05 00 00 44 8b 65 00 4d 8d 6e 58 4c
RSP: 0018:ffffc90000007a80 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88802a8dc290 RCX: ffff88802e52bc00
RDX: 0000000000000101 RSI: 0000000000000000 RDI: ffff88802a8dc240
RBP: 0000000000000000 R08: ffffffff895fbd7a R09: 1ffffffff1f5d135
R10: dffffc0000000000 R11: fffffbfff1f5d136 R12: 0000000000000002
R13: ffffc900034ff7c0 R14: ffff88802a8dc240 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3025ffff CR3: 000000000e134000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 __cpu_map_flush+0x5d/0xd0 kernel/bpf/cpumap.c:765
 xdp_do_check_flushed+0x136/0x240 net/core/filter.c:4304
 __napi_poll+0xe4/0x490 net/core/dev.c:6774
 napi_poll net/core/dev.c:6840 [inline]
 net_rx_action+0x89b/0x1240 net/core/dev.c:6962
 handle_softirqs+0x2c4/0x970 kernel/softirq.c:554
 __do_softirq kernel/softirq.c:588 [inline]
 invoke_softirq kernel/softirq.c:428 [inline]
 __irq_exit_rcu+0xf4/0x1c0 kernel/softirq.c:637
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:649
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1043 [inline]
 sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1043
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:173 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:236 [inline]
RIP: 0010:__sanitizer_cov_trace_switch+0x9d/0x120 kernel/kcov.c:341
Code: 00 00 4d 85 d2 0f 84 8b 00 00 00 4c 8b 4c 24 20 65 4c 8b 1c 25 40 d5 03 00 31 d2 eb 08 48 ff c2 49 39 d2 74 71 4c 8b 74 d6 10 <65> 8b 05 64 8c 70 7e a9 00 01 ff 00 74 11 a9 00 01 00 00 74 de 41
RSP: 0018:ffffc900034ff280 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88802e52bc00
RDX: 0000000000000006 RSI: ffffffff8e1a32a0 RDI: 0000000000000004
RBP: 0000000000000004 R08: 0000000000000005 R09: ffffffff81410f0e
R10: 0000000000000008 R11: ffff88802e52bc00 R12: ffffffff9027c0cc
R13: dffffc0000000000 R14: 0000000000000008 R15: 1ffff9200069fe70
 unwind_next_frame+0x7be/0x2a00 arch/x86/kernel/unwind_orc.c:515
 arch_stack_walk+0x151/0x1b0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x118/0x1d0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
 poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
 __kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2235 [inline]
 slab_free mm/slub.c:4464 [inline]
 kmem_cache_free+0x145/0x350 mm/slub.c:4539
 vma_lock_free kernel/fork.c:455 [inline]
 __vm_area_free+0xe0/0x110 kernel/fork.c:511
 remove_vma mm/mmap.c:146 [inline]
 exit_mmap+0x645/0xc80 mm/mmap.c:3365
 __mmput+0x115/0x380 kernel/fork.c:1343
 exit_mm+0x220/0x310 kernel/exit.c:566
 do_exit+0x9b2/0x27f0 kernel/exit.c:864
 do_group_exit+0x207/0x2c0 kernel/exit.c:1026
 get_signal+0x16a1/0x1740 kernel/signal.c:2917
 arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff317375b59
Code: Unable to access opcode bytes at 0x7ff317375b2f.
RSP: 002b:00007ff3180f50f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007ff317505f68 RCX: 00007ff317375b59
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007ff317505f68
RBP: 00007ff317505f60 R08: 00007ff3180f56c0 R09: 00007ff3180f56c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff317505f6c
R13: 000000000000000b R14: 00007ffc63823320 R15: 00007ffc63823408
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bq_flush_to_queue+0x44/0x610 kernel/bpf/cpumap.c:675
Code: df e8 30 d9 d6 ff 49 8d 5e 50 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 d6 cd 39 00 48 8b 2b 48 89 e8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 1d 05 00 00 44 8b 65 00 4d 8d 6e 58 4c
RSP: 0018:ffffc90000007a80 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88802a8dc290 RCX: ffff88802e52bc00
RDX: 0000000000000101 RSI: 0000000000000000 RDI: ffff88802a8dc240
RBP: 0000000000000000 R08: ffffffff895fbd7a R09: 1ffffffff1f5d135
R10: dffffc0000000000 R11: fffffbfff1f5d136 R12: 0000000000000002
R13: ffffc900034ff7c0 R14: ffff88802a8dc240 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3025ffff CR3: 000000000e134000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	e8 30 d9 d6 ff       	call   0xffd6d935
   5:	49 8d 5e 50          	lea    0x50(%r14),%rbx
   9:	48 89 d8             	mov    %rbx,%rax
   c:	48 c1 e8 03          	shr    $0x3,%rax
  10:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1)
  15:	74 08                	je     0x1f
  17:	48 89 df             	mov    %rbx,%rdi
  1a:	e8 d6 cd 39 00       	call   0x39cdf5
  1f:	48 8b 2b             	mov    (%rbx),%rbp
  22:	48 89 e8             	mov    %rbp,%rax
  25:	48 c1 e8 03          	shr    $0x3,%rax
* 29:	42 0f b6 04 38       	movzbl (%rax,%r15,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	0f 85 1d 05 00 00    	jne    0x553
  36:	44 8b 65 00          	mov    0x0(%rbp),%r12d
  3a:	4d 8d 6e 58          	lea    0x58(%r14),%r13
  3e:	4c                   	rex.WR


Tested on:

commit:         2c9b3512 Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=128d0ae6980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f4925140c45a2a50
dashboard link: https://syzkaller.appspot.com/bug?extid=707d98c8649695eaf329
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1346ca3d980000