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Message-ID: <072ad6df-9136-bfb9-e260-f6003e7d8777@intel.com>
Date: Mon, 27 Apr 2020 14:35:34 +0800
From: Ma Xinjian <max.xinjian@...el.com>
To: john.fastabend@...il.com, alexei.starovoitov@...il.com,
bpf@...r.kernel.org, daniel@...earbox.net, ecree@...arflare.com,
netdev@...r.kernel.org, yhs@...com
Subject: Re: [bpf-next PATCH 03/10] bpf: verifer, adjust_scalar_min_max_vals
to always call update_reg_bounds()
Hi, John.
During our test, we noticed this commit not only cause test_verifier error
"bpf: test_verifier, #70 error message updates for 32-bit right shift"
But also cause test_align error:
```
"Test 9: dubious pointer arithmetic ... Failed to find match 7:
R5_w=inv(id=0,var_off=(0x2; 0xfffffffffffffffc))"
"Test 10: variable subtraction ... Failed to find match 12:
R6=inv(id=0,smin_value=-1006,smax_value=1034,var_off=(0x2;
0xfffffffffffffffc))"
```
clang/llvm version: 11.0.0
Whole error message please refer to the attachment.
part of error info:
```
# Test 9: dubious pointer arithmetic ... Failed to find match 7:
R5_w=inv(id=0,var_off=(0x2; 0xfffffffffffffffc))
# func#0 @0
# 0: R1=ctx(id=0,off=0,imm=0) R10=fp0
# 0: (61) r2 = *(u32 *)(r1 +76)
# 1: R1=ctx(id=0,off=0,imm=0) R2_w=pkt(id=0,off=0,r=0,imm=0) R10=fp0
# 1: (61) r3 = *(u32 *)(r1 +80)
# 2: R1=ctx(id=0,off=0,imm=0) R2_w=pkt(id=0,off=0,r=0,imm=0)
R3_w=pkt_end(id=0,off=0,imm=0) R10=fp0
# 2: (b7) r0 = 0
# 3: R0_w=inv0 R1=ctx(id=0,off=0,imm=0) R2_w=pkt(id=0,off=0,r=0,imm=0)
R3_w=pkt_end(id=0,off=0,imm=0) R10=fp0
# 3: (bf) r5 = r3
# 4: R0_w=inv0 R1=ctx(id=0,off=0,imm=0) R2_w=pkt(id=0,off=0,r=0,imm=0)
R3_w=pkt_end(id=0,off=0,imm=0) R5_w=pkt_end(id=0,off=0,imm=0) R10=fp0
# 4: (1f) r5 -= r2
# 5: R0_w=inv0 R1=ctx(id=0,off=0,imm=0) R2_w=pkt(id=0,off=0,r=0,imm=0)
R3_w=pkt_end(id=0,off=0,imm=0) R5_w=inv(id=0) R10=fp0
# 5: (67) r5 <<= 2
# 6: R0_w=inv0 R1=ctx(id=0,off=0,imm=0) R2_w=pkt(id=0,off=0,r=0,imm=0)
R3_w=pkt_end(id=0,off=0,imm=0)
R5_w=inv(id=0,smax_value=9223372036854775804,umax_value=18446744073709551612,var_off=(0x0;
0xfffffffffffffffc)) R10=fp0
# 6: (07) r5 += 14
[snip]
# 15: (61) r4 = *(u32 *)(r6 +0)
# invalid access to packet, off=0 size=4, R6(id=1,off=0,r=0)
# R6 offset is outside of the packet
# processed 16 insns (limit 1000000) max_states_per_insn 0 total_states
1 peak_states 1 mark_read 1
# FAIL
# Test 10: variable subtraction ... Failed to find match 12:
R6=inv(id=0,smin_value=-1006,smax_value=1034,var_off=(0x2;
0xfffffffffffffffc))
# func#0 @0
# 0: R1=ctx(id=0,off=0,imm=0) R10=fp0
# 0: (61) r2 = *(u32 *)(r1 +76)
# 1: R1=ctx(id=0,off=0,imm=0) R2_w=pkt(id=0,off=0,r=0,imm=0) R10=fp0
# 1: (61) r3 = *(u32 *)(r1 +80)
# 2: R1=ctx(id=0,off=0,imm=0) R2_w=pkt(id=0,off=0,r=0,imm=0)
R3_w=pkt_end(id=0,off=0,imm=0) R10=fp0
# 2: (bf) r0 = r2
# 3: R0_w=pkt(id=0,off=0,r=0,imm=0) R1=ctx(id=0,off=0,imm=0)
R2_w=pkt(id=0,off=0,r=0,imm=0) R3_w=pkt_end(id=0,off=0,imm=0) R10=fp0
# 3: (07) r0 += 8
# 4: R0_w=pkt(id=0,off=8,r=0,imm=0) R1=ctx(id=0,off=0,imm=0)
R2_w=pkt(id=0,off=0,r=0,imm=0) R3_w=pkt_end(id=0,off=0,imm=0) R10=fp0
# 4: (3d) if r3 >= r0 goto pc+1
# R0_w=pkt(id=0,off=8,r=0,imm=0) R1=ctx(id=0,off=0,imm=0)
R2_w=pkt(id=0,off=0,r=0,imm=0) R3_w=pkt_end(id=0,off=0,imm=0) R10=fp0
# 5: R0_w=pkt(id=0,off=8,r=0,imm=0) R1=ctx(id=0,off=0,imm=0)
R2_w=pkt(id=0,off=0,r=0,imm=0) R3_w=pkt_end(id=0,off=0,imm=0) R10=fp0
# 5: (95) exit
# 6: R0_w=pkt(id=0,off=8,r=8,imm=0) R1=ctx(id=0,off=0,imm=0)
R2_w=pkt(id=0,off=0,r=8,imm=0) R3_w=pkt_end(id=0,off=0,imm=0) R10=fp0
# 6: (71) r6 = *(u8 *)(r2 +0)
# 7: R0_w=pkt(id=0,off=8,r=8,imm=0) R1=ctx(id=0,off=0,imm=0)
R2_w=pkt(id=0,off=0,r=8,imm=0) R3_w=pkt_end(id=0,off=0,imm=0)
R6_w=inv(id=0,umax_value=255,var_off=(0x0; 0xff)) R10=fp0
# 7: (bf) r7 = r6
[snip]
```
---
Best Regards.
Ma Xinjian
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