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Fix overflow in conversion from uvalue to svalue #769

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merged 9 commits into from
Oct 30, 2024
Merged

Fix overflow in conversion from uvalue to svalue #769

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da857be
Fix overflow in conversion from uvalue to svalue
Oct 30, 2024
087156b
Add positive and negative test cases
Oct 30, 2024
0167dd0
PR feedback
Oct 30, 2024
b08fffe
Add test to ensure immediate and register versions of unsigned right …
Oct 30, 2024
609e11f
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f4c915a
PR feedback and fix other cases
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9 changes: 3 additions & 6 deletions src/crab/ebpf_domain.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2374,12 +2374,9 @@ void ebpf_domain_t::lshr(const Reg& dst_reg, int imm, int finite_width) {
}
}
m_inv.set(dst.uvalue, interval_t{lb_n, ub_n});
if (ub_n.narrow<int64_t>() >= lb_n.narrow<int64_t>()) {
// ? m_inv.set(dst.svalue, crab::interval_t{number_t{(int64_t)lb_n}, number_t{(int64_t)ub_n}});
m_inv.assign(dst.svalue, dst.uvalue);
} else {
havoc(dst.svalue);
}
m_inv.assign(dst.svalue, dst.uvalue);
overflow_signed(m_inv, dst.svalue, finite_width);
overflow_unsigned(m_inv, dst.uvalue, finite_width);
return;
}
havoc(dst.svalue);
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164 changes: 164 additions & 0 deletions test-data/shift.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -1104,3 +1104,167 @@ post:
- r2.type=number
- r2.svalue=32
- r2.uvalue=32

---
test-case: check that unsigned right shift by 0 is idempotent - svalue out of range

pre:
- r0.type=number
# This is 0x8000000000000000, which is out of range for a signed 64-bit number.
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- r0.svalue=-9223372036854775808
- r0.uvalue=9223372036854775808
- r1.type=number
- r1.svalue=-9223372036854775808
- r1.uvalue=9223372036854775808

code:
<start>: |
r0 >>= 0
if r1 == r0 goto <one>
r2 = 0
exit
<one>: |
r2 = 1
exit

post:
- r0.type=number
- r0.svalue=-9223372036854775808
- r0.uvalue=9223372036854775808
- r1.type=number
- r1.svalue=-9223372036854775808
- r1.uvalue=9223372036854775808
- r0.svalue=r1.svalue
- r0.uvalue=r1.uvalue
- r2.svalue=1
- r2.type=number
- r2.uvalue=1

messages:
- "1:2: Code is unreachable after 1:2"

---
test-case: check that unsigned right shift by 0 is idempotent - valid svalue

pre:
- r0.type=number
# This is 0x7fffffffffffffff, which is in range for a signed 64-bit number.
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- r0.svalue=9223372036854775807
- r0.uvalue=9223372036854775807
- r1.type=number
- r1.svalue=9223372036854775807
- r1.uvalue=9223372036854775807

code:
<start>: |
r0 >>= 0
if r1 == r0 goto <one>
r2 = 0
exit
<one>: |
r2 = 1
exit

post:
- r0.svalue=9223372036854775807
- r0.svalue=r1.svalue
- r0.type=number
- r0.uvalue=9223372036854775807
- r0.uvalue=r1.uvalue
- r1.svalue=9223372036854775807
- r1.type=number
- r1.uvalue=9223372036854775807
- r2.svalue=1
- r2.type=number
- r2.uvalue=1

messages:
- "1:2: Code is unreachable after 1:2"

---
test-case: check that unsigned right shift by 0 is idempotent - svalue out of range - via register

pre:
- r0.type=number
# This is 0x8000000000000000, which is out of range for a signed 64-bit number.
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- r0.svalue=-9223372036854775808
- r0.uvalue=9223372036854775808
- r1.type=number
- r1.svalue=-9223372036854775808
- r1.uvalue=9223372036854775808
- r3.type=number
- r3.uvalue=0
- r3.svalue=0

code:
<start>: |
r0 >>= r3
if r1 == r0 goto <one>
r2 = 0
exit
<one>: |
r2 = 1
exit

post:
- r0.type=number
- r0.svalue=-9223372036854775808
- r0.uvalue=9223372036854775808
- r1.type=number
- r1.svalue=-9223372036854775808
- r1.uvalue=9223372036854775808
- r0.svalue=r1.svalue
- r0.uvalue=r1.uvalue
- r2.svalue=1
- r2.type=number
- r2.uvalue=1
- r3.type=number
- r3.uvalue=0
- r3.svalue=0

messages:
- "1:2: Code is unreachable after 1:2"

---
test-case: check that unsigned right shift by 0 is idempotent - valid svalue

pre:
- r0.type=number
# This is 0x7fffffffffffffff, which is in range for a signed 64-bit number.
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- r0.svalue=9223372036854775807
- r0.uvalue=9223372036854775807
- r1.type=number
- r1.svalue=9223372036854775807
- r1.uvalue=9223372036854775807
- r3.type=number
- r3.uvalue=0
- r3.svalue=0

code:
<start>: |
r0 >>= r3
if r1 == r0 goto <one>
r2 = 0
exit
<one>: |
r2 = 1
exit

post:
- r0.svalue=9223372036854775807
- r0.svalue=r1.svalue
- r0.type=number
- r0.uvalue=9223372036854775807
- r0.uvalue=r1.uvalue
- r1.svalue=9223372036854775807
- r1.type=number
- r1.uvalue=9223372036854775807
- r2.svalue=1
- r2.type=number
- r2.uvalue=1
- r3.type=number
- r3.uvalue=0
- r3.svalue=0

messages:
- "1:2: Code is unreachable after 1:2"
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