BUG: unable to handle kernel paging request in bpf_dispatcher_xdp

[Hao Sun]

Hi,

The following crash can be triggered with the BPF prog provided.
It seems the verifier passed some invalid progs. I will try to simplify
the C reproducer, for now, the following can reproduce this:

HEAD commit: ab0350c743d5 selftests/bpf: Fix conflicts with built-in
functions in bpf_iter_ksym
git tree: bpf-next
console log: https://pastebin.com/raw/87RCSnCs
kernel config: https://pastebin.com/raw/rZdWLcgK
Syz reproducer: https://pastebin.com/raw/4kbwhdEv
C reproducer: https://pastebin.com/raw/GFfDn2Gk

wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50
wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50
IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready
BUG: unable to handle page fault for address: 000000000fe0840f
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 2ebe3067 P4D 2ebe3067 PUD 1dd9b067 PMD 0
Oops: 0002 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 7536 Comm: a.out Not tainted
6.1.0-rc7-01489-gab0350c743d5-dirty #118
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux
1.16.1-1-1 04/01/2014
RIP: 0010:bpf_dispatcher_xdp+0x24/0x1000
Code: cc cc cc cc cc cc 48 81 fa e8 55 00 a0 0f 8f 63 00 00 00 48 81
fa d8 54 00 a0 7f 2a 48 81 fa 4c 53 00 a0 7f 11 48 81 fa 4c 53 <00> a0
0f 84 e0 0f 00 00 ff e2 66 90 48 81 fa d8 54 00 a0 0f 84 5b
RSP: 0018:ffffc900029df908 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffc900028b9000 RCX: 0000000000000000
RDX: ffffffffa000534c RSI: ffffc900028b9048 RDI: ffffc900029dfb70
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000001 R14: ffffc900028b9030 R15: ffffc900029dfb50
FS:  00007ff249efc700(0000) GS:ffff888063a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000fe0840f CR3: 000000002e0ba000 CR4: 0000000000750ef0
PKRU: 55555554
Call Trace:
 <TASK>
 ? __bpf_prog_run include/linux/filter.h:600 [inline]
 ? bpf_prog_run_xdp include/linux/filter.h:775 [inline]
 ? bpf_test_run+0x2ce/0x990 net/bpf/test_run.c:400
 ? bpf_test_timer_continue+0x3d0/0x3d0 net/bpf/test_run.c:79
 ? bpf_dispatcher_xdp+0x800/0x1000
 ? bpf_dispatcher_xdp+0x800/0x1000
 ? bpf_dispatcher_xdp+0x800/0x1000
 ? _copy_from_user+0x5f/0x180 lib/usercopy.c:21
 ? bpf_test_init.isra.0+0x111/0x150 net/bpf/test_run.c:772
 ? bpf_prog_test_run_xdp+0xbde/0x1400 net/bpf/test_run.c:1389
 ? bpf_prog_test_run_skb+0x1dd0/0x1dd0 include/linux/skbuff.h:2594
 ? rcu_lock_release include/linux/rcupdate.h:321 [inline]
 ? rcu_read_unlock include/linux/rcupdate.h:783 [inline]
 ? __fget_files+0x283/0x3e0 fs/file.c:914
 ? fput+0x30/0x1a0 fs/file_table.c:371
 ? ____bpf_prog_get kernel/bpf/syscall.c:2206 [inline]
 ? __bpf_prog_get+0x9a/0x2e0 kernel/bpf/syscall.c:2270
 ? bpf_prog_test_run_skb+0x1dd0/0x1dd0 include/linux/skbuff.h:2594
 ? bpf_prog_test_run kernel/bpf/syscall.c:3644 [inline]
 ? __sys_bpf+0x1293/0x5840 kernel/bpf/syscall.c:4997
 ? futex_wait_setup+0x230/0x230 kernel/futex/waitwake.c:625
 ? bpf_perf_link_attach+0x520/0x520 kernel/bpf/syscall.c:2720
 ? instrument_atomic_read include/linux/instrumented.h:72 [inline]
 ? atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
 ? queued_spin_is_locked include/asm-generic/qspinlock.h:57 [inline]
 ? debug_spin_unlock kernel/locking/spinlock_debug.c:100 [inline]
 ? do_raw_spin_unlock+0x53/0x230 kernel/locking/spinlock_debug.c:140
 ? futex_wake+0x15b/0x4a0 kernel/futex/waitwake.c:161
 ? do_futex+0x130/0x350 kernel/futex/syscalls.c:122
 ? __ia32_sys_get_robust_list+0x3b0/0x3b0 kernel/futex/syscalls.c:72
 ? __do_sys_bpf kernel/bpf/syscall.c:5083 [inline]
 ? __se_sys_bpf kernel/bpf/syscall.c:5081 [inline]
 ? __x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5081
 ? syscall_enter_from_user_mode+0x26/0xb0 kernel/entry/common.c:111
 ? do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 ? do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
 ? entry_SYSCALL_64_after_hwframe+0x63/0xcd
 </TASK>
Modules linked in:
Dumping ftrace buffer:
   (ftrace buffer empty)
CR2: 000000000fe0840f
---[ end trace 0000000000000000 ]---
RIP: 0010:bpf_dispatcher_xdp+0x24/0x1000
Code: cc cc cc cc cc cc 48 81 fa e8 55 00 a0 0f 8f 63 00 00 00 48 81
fa d8 54 00 a0 7f 2a 48 81 fa 4c 53 00 a0 7f 11 48 81 fa 4c 53 <00> a0
0f 84 e0 0f 00 00 ff e2 66 90 48 81 fa d8 54 00 a0 0f 84 5b
RSP: 0018:ffffc900029df908 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffc900028b9000 RCX: 0000000000000000
RDX: ffffffffa000534c RSI: ffffc900028b9048 RDI: ffffc900029dfb70
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000001 R14: ffffc900028b9030 R15: ffffc900029dfb50
FS:  00007ff249efc700(0000) GS:ffff888063a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000fe0840f CR3: 000000002e0ba000 CR4: 0000000000750ef0
PKRU: 55555554