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

[syzbot <syzbot+707d98c8649695eaf329@syzkaller.appspotmail.com>]

Hello,

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

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
CPU: 0 PID: 7230 Comm: syz.0.654 Not tainted 6.10.0-rc6-syzkaller-01232-gfecef4cd42c6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
RIP: 0010:__xsk_map_flush+0x56/0x2b0
Code: 80 3c 28 00 74 08 48 89 df e8 96 68 92 f6 4c 8b 3b 49 39 df 0f 84 43 02 00 00 48 89 1c 24 4c 89 f8 48 c1 e8 03 48 89 44 24 08 <42> 80 3c 28 00 74 08 4c 89 ff e8 6b 68 92 f6 49 8b 07 48 89 44 24
RSP: 0018:ffffc90000007ae8 EFLAGS: 00010203
RAX: 0000000000000008 RBX: ffffc90004087820 RCX: ffff88807b148000
RDX: 0000000080000101 RSI: 0000000000000010 RDI: ffffc90004087820
RBP: dffffc0000000000 R08: ffffffff8959f41a R09: 1ffffffff1f5941d
R10: dffffc0000000000 R11: fffffbfff1f5941e R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000010 R15: 0000000000000046
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd8bf106030 CR3: 000000001e6d4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 xdp_do_check_flushed+0x18e/0x240 net/core/filter.c:4308
 __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:__raw_write_unlock_irq include/linux/rwlock_api_smp.h:274 [inline]
RIP: 0010:_raw_write_unlock_irq+0x29/0x50 kernel/locking/spinlock.c:358
Code: 90 f3 0f 1e fa 53 48 89 fb 48 83 c7 18 48 8b 74 24 08 e8 7a de e6 f5 48 89 df e8 52 33 e8 f5 e8 cd d9 11 f6 fb bf 01 00 00 00 <e8> 22 ee d9 f5 65 8b 05 a3 26 78 74 85 c0 74 06 5b c3 cc cc cc cc
RSP: 0018:ffffc90004087ab0 EFLAGS: 00000282
RAX: 4c2770ac48549a00 RBX: ffffffff8e00a040 RCX: ffffffff9477c603
RDX: dffffc0000000000 RSI: ffffffff8bcabb40 RDI: 0000000000000001
RBP: ffffc90004087c20 R08: ffffffff8faca0ef R09: 1ffffffff1f5941d
R10: dffffc0000000000 R11: fffffbfff1f5941e R12: 1ffff1100f6290ad
R13: 1ffff1100f6290ac R14: ffff88801fc4bcc0 R15: dffffc0000000000
 exit_notify kernel/exit.c:768 [inline]
 do_exit+0x19c4/0x27e0 kernel/exit.c:896
 do_group_exit+0x207/0x2c0 kernel/exit.c:1025
 get_signal+0x16a1/0x1740 kernel/signal.c:2909
 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+0xc9/0x360 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd8bef75b59
Code: Unable to access opcode bytes at 0x7fd8bef75b2f.
RSP: 002b:00007fd8bfe150f8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fd8bf105f68 RCX: 00007fd8bef75b59
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fd8bf105f68
RBP: 00007fd8bf105f60 R08: 00007fd8bfe156c0 R09: 00007fd8bfe156c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd8bf105f6c
R13: 000000000000000b R14: 00007ffd2583fbe0 R15: 00007ffd2583fcc8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__xsk_map_flush+0x56/0x2b0
Code: 80 3c 28 00 74 08 48 89 df e8 96 68 92 f6 4c 8b 3b 49 39 df 0f 84 43 02 00 00 48 89 1c 24 4c 89 f8 48 c1 e8 03 48 89 44 24 08 <42> 80 3c 28 00 74 08 4c 89 ff e8 6b 68 92 f6 49 8b 07 48 89 44 24
RSP: 0018:ffffc90000007ae8 EFLAGS: 00010203
RAX: 0000000000000008 RBX: ffffc90004087820 RCX: ffff88807b148000
RDX: 0000000080000101 RSI: 0000000000000010 RDI: ffffc90004087820
RBP: dffffc0000000000 R08: ffffffff8959f41a R09: 1ffffffff1f5941d
R10: dffffc0000000000 R11: fffffbfff1f5941e R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000010 R15: 0000000000000046
FS:  0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd8bf106030 CR3: 000000000e132000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	80 3c 28 00          	cmpb   $0x0,(%rax,%rbp,1)
   4:	74 08                	je     0xe
   6:	48 89 df             	mov    %rbx,%rdi
   9:	e8 96 68 92 f6       	call   0xf69268a4
   e:	4c 8b 3b             	mov    (%rbx),%r15
  11:	49 39 df             	cmp    %rbx,%r15
  14:	0f 84 43 02 00 00    	je     0x25d
  1a:	48 89 1c 24          	mov    %rbx,(%rsp)
  1e:	4c 89 f8             	mov    %r15,%rax
  21:	48 c1 e8 03          	shr    $0x3,%rax
  25:	48 89 44 24 08       	mov    %rax,0x8(%rsp)
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 ff             	mov    %r15,%rdi
  34:	e8 6b 68 92 f6       	call   0xf69268a4
  39:	49 8b 07             	mov    (%r15),%rax
  3c:	48                   	rex.W
  3d:	89                   	.byte 0x89
  3e:	44                   	rex.R
  3f:	24                   	.byte 0x24


Tested on:

commit:         fecef4cd tun: Assign missing bpf_net_context.
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=10ed355e980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8defeae77515c9b1
dashboard link: https://syzkaller.appspot.com/bug?extid=707d98c8649695eaf329
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.