Hi, BPF community,
I would like to report a possible bug in bpf-next,
hope I don't make any stupid mistake. Here is the details:
I have two VMs:
One has the kernel built against the following commit:
0693b27644f04852e46f7f034e3143992b658869 (bpf-next)
The ksnoop tool (from BCC repo) works well on this VM.
Another has the kernel built against the following commit:
5319255b8df9271474bc9027cabf82253934f28d (bpf-next)
On this VM, the ksnoop tool failed with the following message:
libbpf: load bpf program failed: Permission denied
libbpf: -- BEGIN DUMP LOG ---
libbpf:
R1 type=ctx expected=fp
; return ksnoop(ctx, false);
0: (b7) r2 = 0
1: (85) call pc+2
caller:
R10=fp0
callee:
frame1: R1=ctx(id=0,off=0,imm=0) R2_w=invP0 R10=fp0
; static int ksnoop(struct pt_regs *ctx, bool entry)
4: (7b) *(u64 *)(r10 -168) = r2
5: (bf) r9 = r1
; task = bpf_get_current_task();
6: (85) call bpf_get_current_task#35
; task = bpf_get_current_task();
7: (7b) *(u64 *)(r10 -16) = r0
8: (bf) r2 = r10
;
9: (07) r2 += -16
; func_stack = bpf_map_lookup_elem(&ksnoop_func_stack, &task);
10: (18) r1 = 0xffff8c70353f3c00
12: (85) call bpf_map_lookup_elem#1
13: (bf) r7 = r0
; if (!func_stack) {
14: (55) if r7 != 0x0 goto pc+35
frame1: R0=invP0 R7_w=invP0 R9=ctx(id=0,off=0,imm=0) R10=fp0 fp-16=mmmmmmmm fp-168=00000000
15: (b7) r1 = 0
; struct func_stack new_stack = {};
16: (7b) *(u64 *)(r10 -24) = r1
17: (7b) *(u64 *)(r10 -32) = r1
18: (7b) *(u64 *)(r10 -40) = r1
19: (7b) *(u64 *)(r10 -48) = r1
20: (7b) *(u64 *)(r10 -56) = r1
21: (7b) *(u64 *)(r10 -64) = r1
22: (7b) *(u64 *)(r10 -72) = r1
23: (7b) *(u64 *)(r10 -80) = r1
24: (7b) *(u64 *)(r10 -88) = r1
25: (7b) *(u64 *)(r10 -96) = r1
26: (7b) *(u64 *)(r10 -104) = r1
27: (7b) *(u64 *)(r10 -112) = r1
28: (7b) *(u64 *)(r10 -120) = r1
29: (7b) *(u64 *)(r10 -128) = r1
30: (7b) *(u64 *)(r10 -136) = r1
31: (7b) *(u64 *)(r10 -144) = r1
32: (7b) *(u64 *)(r10 -152) = r1
; new_stack.task = task;
33: (79) r1 = *(u64 *)(r10 -16)
; new_stack.task = task;
34: (7b) *(u64 *)(r10 -160) = r1
35: (bf) r7 = r10
; struct func_stack new_stack = {};
36: (07) r7 += -16
37: (bf) r3 = r10
38: (07) r3 += -160
; bpf_map_update_elem(&ksnoop_func_stack, &task, &new_stack,
39: (18) r1 = 0xffff8c70353f3c00
41: (bf) r2 = r7
42: (b7) r4 = 1
43: (85) call bpf_map_update_elem#2
; func_stack = bpf_map_lookup_elem(&ksnoop_func_stack, &task);
44: (18) r1 = 0xffff8c70353f3c00
46: (bf) r2 = r7
47: (85) call bpf_map_lookup_elem#1
48: (bf) r7 = r0
49: (15) if r7 == 0x0 goto pc+483
frame1: R0_w=map_value(id=0,off=0,ks=8,vs=144,imm=0) R7_w=map_value(id=0,off=0,ks=8,vs=144,imm=0) R9=ctx(id=0,off=0,imm=0) R10=fp0 fp-16=mmmmmmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm fp-56=mmmmmmmm fp-64=mmmmmmmm fp-72=mmmmmmmm fp-80=mmmmmmmm fp-88=mmmmmmmm fp-96=mmmmmmmm fp-104=mmmmmmmm fp-112=mmmmmmmm fp-120=mmmmmmmm fp-128=mmmmmmmm fp-136=mmmmmmmm fp-144=mmmmmmmm fp-152=mmmmmmmm fp-160=mmmmmmmm fp-168=00000000
; stack_depth = func_stack->stack_depth;
50: (71) r6 = *(u8 *)(r7 +136)
frame1: R0_w=map_value(id=0,off=0,ks=8,vs=144,imm=0) R7_w=map_value(id=0,off=0,ks=8,vs=144,imm=0) R9=ctx(id=0,off=0,imm=0) R10=fp0 fp-16=mmmmmmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm fp-56=mmmmmmmm fp-64=mmmmmmmm fp-72=mmmmmmmm fp-80=mmmmmmmm fp-88=mmmmmmmm fp-96=mmmmmmmm fp-104=mmmmmmmm fp-112=mmmmmmmm fp-120=mmmmmmmm fp-128=mmmmmmmm fp-136=mmmmmmmm fp-144=mmmmmmmm fp-152=mmmmmmmm fp-160=mmmmmmmm fp-168=00000000
; if (stack_depth > FUNC_MAX_STACK_DEPTH)
51: (25) if r6 > 0x10 goto pc+481
frame1: R0_w=map_value(id=0,off=0,ks=8,vs=144,imm=0) R6_w=invP(id=0,umax_value=16,var_off=(0x0; 0xff),s32_max_value=255,u32_max_value=255) R7_w=map_value(id=0,off=0,ks=8,vs=144,imm=0) R9=ctx(id=0,off=0,imm=0) R10=fp0 fp-16=mmmmmmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm fp-56=mmmmmmmm fp-64=mmmmmmmm fp-72=mmmmmmmm fp-80=mmmmmmmm fp-88=mmmmmmmm fp-96=mmmmmmmm fp-104=mmmmmmmm fp-112=mmmmmmmm fp-120=mmmmmmmm fp-128=mmmmmmmm fp-136=mmmmmmmm fp-144=mmmmmmmm fp-152=mmmmmmmm fp-160=mmmmmmmm fp-168=00000000
; if (entry) {
52: (79) r1 = *(u64 *)(r10 -168)
53: (15) if r1 == 0x0 goto pc+74
; if (stack_depth == 0 || stack_depth >= FUNC_MAX_STACK_DEPTH)
128: (15) if r6 == 0x0 goto pc+404
frame1: R0=map_value(id=0,off=0,ks=8,vs=144,imm=0) R1=invP0 R6=invP(id=0,umax_value=16,var_off=(0x0; 0x1f)) R7=map_value(id=0,off=0,ks=8,vs=144,imm=0) R9=ctx(id=0,off=0,imm=0) R10=fp0 fp-16=mmmmmmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm fp-56=mmmmmmmm fp-64=mmmmmmmm fp-72=mmmmmmmm fp-80=mmmmmmmm fp-88=mmmmmmmm fp-96=mmmmmmmm fp-104=mmmmmmmm fp-112=mmmmmmmm fp-120=mmmmmmmm fp-128=mmmmmmmm fp-136=mmmmmmmm fp-144=mmmmmmmm fp-152=mmmmmmmm fp-160=mmmmmmmm fp-168=00000000
129: (25) if r6 > 0xf goto pc+403
frame1: R0=map_value(id=0,off=0,ks=8,vs=144,imm=0) R1=invP0 R6=invP(id=0,umax_value=15,var_off=(0x0; 0x1f),s32_max_value=16,u32_max_value=16) R7=map_value(id=0,off=0,ks=8,vs=144,imm=0) R9=ctx(id=0,off=0,imm=0) R10=fp0 fp-16=mmmmmmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm fp-56=mmmmmmmm fp-64=mmmmmmmm fp-72=mmmmmmmm fp-80=mmmmmmmm fp-88=mmmmmmmm fp-96=mmmmmmmm fp-104=mmmmmmmm fp-112=mmmmmmmm fp-120=mmmmmmmm fp-128=mmmmmmmm fp-136=mmmmmmmm fp-144=mmmmmmmm fp-152=mmmmmmmm fp-160=mmmmmmmm fp-168=00000000
130: (b7) r1 = 0
; if (stack_depth > 0)
131: (15) if r6 == 0x0 goto pc+2
frame1: R0=map_value(id=0,off=0,ks=8,vs=144,imm=0) R1_w=invP0 R6=invP(id=0,umax_value=15,var_off=(0x0; 0xf)) R7=map_value(id=0,off=0,ks=8,vs=144,imm=0) R9=ctx(id=0,off=0,imm=0) R10=fp0 fp-16=mmmmmmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm fp-56=mmmmmmmm fp-64=mmmmmmmm fp-72=mmmmmmmm fp-80=mmmmmmmm fp-88=mmmmmmmm fp-96=mmmmmmmm fp-104=mmmmmmmm fp-112=mmmmmmmm fp-120=mmmmmmmm fp-128=mmmmmmmm fp-136=mmmmmmmm fp-144=mmmmmmmm fp-152=mmmmmmmm fp-160=mmmmmmmm fp-168=00000000
132: (bf) r1 = r6
133: (07) r1 += -1
; ip = func_stack->ips[stack_depth];
134: (bf) r2 = r1
135: (57) r2 &= 255
136: (67) r2 <<= 3
; last_ip = func_stack->ips[last_stack_depth];
137: (bf) r3 = r7
138: (07) r3 += 8
; ip = func_stack->ips[stack_depth];
139: (bf) r4 = r3
140: (0f) r4 += r2
; last_ip = func_stack->ips[last_stack_depth];
141: (67) r6 <<= 3
142: (0f) r3 += r6
; ip = func_stack->ips[stack_depth];
143: (79) r2 = *(u64 *)(r4 +0)
frame1: R0=map_value(id=0,off=0,ks=8,vs=144,imm=0) R1_w=invP(id=4,smin_value=-1,smax_value=14) R2_w=invP(id=0,umax_value=2040,var_off=(0x0; 0x7f8)) R3_w=map_value(id=0,off=8,ks=8,vs=144,umax_value=120,var_off=(0x0; 0x78)) R4_w=map_value(id=0,off=8,ks=8,vs=144,umax_value=2040,var_off=(0x0; 0x7f8)) R6_w=invP(id=0,umax_value=120,var_off=(0x0; 0x78)) R7=map_value(id=0,off=0,ks=8,vs=144,imm=0) R9=ctx(id=0,off=0,imm=0) R10=fp0 fp-16=mmmmmmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm fp-56=mmmmmmmm fp-64=mmmmmmmm fp-72=mmmmmmmm fp-80=mmmmmmmm fp-88=mmmmmmmm fp-96=mmmmmmmm fp-104=mmmmmmmm fp-112=mmmmmmmm fp-120=mmmmmmmm fp-128=mmmmmmmm fp-136=mmmmmmmm fp-144=mmmmmmmm fp-152=mmmmmmmm fp-160=mmmmmmmm fp-168=00000000
invalid access to map value, value_size=144 off=2048 size=8
R4 max value is outside of the allowed memory range
processed 65 insns (limit 1000000) max_states_per_insn 0 total_states 3 peak_states 3 mark_read 2
libbpf: -- END LOG --
libbpf: failed to load program 'kprobe_return'
libbpf: failed to load object 'ksnoop_bpf'
libbpf: failed to load BPF skeleton 'ksnoop_bpf': -4007
Error: Could not load ksnoop BPF: Unknown error 4007
