syzbot
general protection fault in __pcpu_freelist_pop
Status:
premoderation: reported on 2026/05/21 20:42
Reported-by: syzbot+4ec5b08d669d6f71c01f@syzkaller.appspotmail.com
First crash: 123d, last: 8d22h
Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 3646 Comm: syz.3.773 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:___pcpu_freelist_pop kernel/bpf/percpu_freelist.c:134 [inline]
RIP: 0010:__pcpu_freelist_pop+0x777/0x840 kernel/bpf/percpu_freelist.c:188
Code: 00 74 52 48 89 df e8 38 0a 2a 00 eb 48 e8 01 7e e4 ff eb 4b e8 fa 7d e4 ff 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ff e8 1b 09 2a 00 4d 8b 37 48 b8 00 00 00
RSP: 0018:ffffc9000110ed90 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffffe8ffffd10b48 RCX: dffffc0000000000
RDX: ffffc9000260e000 RSI: 000000000000043e RDI: 000000000000043f
RBP: ffffc9000110edd0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000221da4 R12: ffffe8ffffd10b50
R13: 1ffffd1ffffa2169 R14: 0000000000000001 R15: 0000000000000002
FS: 00007f1b001cf6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000008000000002 CR3: 0000000131154000 CR4: 00000000003506b0
DR0: 0000200000000300 DR1: 0100000000000000 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
Call Trace:
<TASK>
pcpu_freelist_pop+0x8a/0xf0 kernel/bpf/percpu_freelist.c:197
__bpf_get_stackid+0x556/0x960 kernel/bpf/stackmap.c:246
____bpf_get_stackid_pe kernel/bpf/stackmap.c:365 [inline]
bpf_get_stackid_pe+0x2ee/0x400 kernel/bpf/stackmap.c:334
bpf_prog_2414a5d5030ea31b+0x21/0x25
bpf_dispatcher_nop_func include/linux/bpf.h:987 [inline]
__bpf_prog_run include/linux/filter.h:607 [inline]
bpf_prog_run include/linux/filter.h:614 [inline]
bpf_overflow_handler+0x3c7/0x5e0 kernel/events/core.c:10273
__perf_event_overflow+0x458/0x640 kernel/events/core.c:9448
perf_swevent_overflow kernel/events/core.c:9531 [inline]
perf_swevent_event+0x243/0x440 kernel/events/core.c:9582
do_perf_sw_event kernel/events/core.c:9695 [inline]
___perf_sw_event+0x3bf/0x500 kernel/events/core.c:9726
__perf_sw_event+0x134/0x270 kernel/events/core.c:9738
perf_sw_event include/linux/perf_event.h:1250 [inline]
do_user_addr_fault+0xfe9/0x1030 arch/x86/mm/fault.c:1285
handle_page_fault arch/x86/mm/fault.c:1464 [inline]
exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1517
asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:copy_user_enhanced_fast_string+0xa/0x40 arch/x86/lib/copy_user_64.S:166
Code: ff c9 75 f2 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 01 ca c3 8d 0c ca 89 ca eb 20 0f 01 cb 83 fa 40 72 38 89 d1 <f3> a4 31 c0 0f 01 ca c3 89 ca eb 0a 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc9000110f5e0 EFLAGS: 00050206
RAX: ffffffff82675001 RBX: 00000000000000cb RCX: 00000000000000cb
RDX: 00000000000000cb RSI: 0000008000000002 RDI: ffff88810d710712
RBP: ffffc9000110f610 R08: ffff88810d7107dc R09: 1ffff11021ae20fb
R10: dffffc0000000000 R11: ffffed1021ae20fc R12: 00007fffffffef35
R13: 0000000000000000 R14: ffff88810d710712 R15: 0000008000000002
_copy_from_iter+0x4e1/0xfe0 lib/iov_iter.c:632
copy_page_from_iter+0x1de/0x2c0 lib/iov_iter.c:752
skb_copy_datagram_from_iter+0x2cb/0x6b0 net/core/datagram.c:581
unix_dgram_sendmsg+0x683/0x1710 net/unix/af_unix.c:1962
sock_sendmsg_nosec net/socket.c:716 [inline]
__sock_sendmsg net/socket.c:728 [inline]
____sys_sendmsg+0x5fb/0x9c0 net/socket.c:2509
___sys_sendmsg+0x2a2/0x360 net/socket.c:2563
__sys_sendmsg net/socket.c:2592 [inline]
__do_sys_sendmsg net/socket.c:2601 [inline]
__se_sys_sendmsg net/socket.c:2599 [inline]
__x64_sys_sendmsg+0x20d/0x2e0 net/socket.c:2599
x64_sys_call+0x171/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f1aff39e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f1b001cf028 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f1aff625fa0 RCX: 00007f1aff39e159
RDX: 0000000000000000 RSI: 0000200000000100 RDI: 000000000000000c
RBP: 00007f1aff43503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1aff626038 R14: 00007f1aff625fa0 R15: 00007ffe8a56cc58
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:___pcpu_freelist_pop kernel/bpf/percpu_freelist.c:134 [inline]
RIP: 0010:__pcpu_freelist_pop+0x777/0x840 kernel/bpf/percpu_freelist.c:188
Code: 00 74 52 48 89 df e8 38 0a 2a 00 eb 48 e8 01 7e e4 ff eb 4b e8 fa 7d e4 ff 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ff e8 1b 09 2a 00 4d 8b 37 48 b8 00 00 00
RSP: 0018:ffffc9000110ed90 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffffe8ffffd10b48 RCX: dffffc0000000000
RDX: ffffc9000260e000 RSI: 000000000000043e RDI: 000000000000043f
RBP: ffffc9000110edd0 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000221da4 R12: ffffe8ffffd10b50
R13: 1ffffd1ffffa2169 R14: 0000000000000001 R15: 0000000000000002
FS: 00007f1b001cf6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000008000000002 CR3: 0000000131154000 CR4: 00000000003506b0
DR0: 0000200000000300 DR1: 0100000000000000 DR2: 0000200000000300
DR3: 0000200000000300 DR6: 00000000ffff0ff0 DR7: 0000000000000600
----------------
Code disassembly (best guess):
0: 00 74 52 48 add %dh,0x48(%rdx,%rdx,2)
4: 89 df mov %ebx,%edi
6: e8 38 0a 2a 00 call 0x2a0a43
b: eb 48 jmp 0x55
d: e8 01 7e e4 ff call 0xffe47e13
12: eb 4b jmp 0x5f
14: e8 fa 7d e4 ff call 0xffe47e13
19: 4c 89 f8 mov %r15,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
27: fc ff df
* 2a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 ff mov %r15,%rdi
33: e8 1b 09 2a 00 call 0x2a0953
38: 4d 8b 37 mov (%r15),%r14
3b: 48 rex.W
3c: b8 .byte 0xb8
3d: 00 00 add %al,(%rax)
Struck through repros no longer work on HEAD.