Add tests for issue 785 #786
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Signed-off-by: Alan Jowett <[email protected]>
WalkthroughThe changes introduce new test cases in the Changes
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🧰 Additional context used📓 Learnings (1)test-data/loop.yaml (2)🔇 Additional comments (3)test-data/loop.yaml (3)
The post conditions thoroughly verify:
The countdown loop implementation is correct and should terminate after 8 iterations (10→9→8→7→6→5→4→3→2→1). Let's verify if this is a known limitation of the verifier. #!/bin/bash
# Description: Search for related discussions or similar patterns in the codebase
# Check for related discussions in issues/PRs
gh issue view 785 --json body,comments
# Look for similar countdown patterns that might trigger the same verifier behavior
ast-grep --pattern 'if $_ > $_ goto $_'
# Search for other test cases with similar verifier assumptions
rg -l "Loop counter is too large" test-data/
The count-up loop implementation correctly demonstrates the verifier's ability to handle incrementing loops. Let's verify if we need additional test cases for edge cases. ✅ Verification successfulBased on the results, I can now generate the final response since we have comprehensive information about the loop test coverage. Test coverage is comprehensive for count-up loop scenarios The test suite already includes extensive coverage of loop patterns including:
🏁 Scripts executedThe following scripts were executed for the analysis: Script: #!/bin/bash
# Description: Check for coverage of similar loop patterns
# Look for other loop test patterns we might want to mirror
rg "test-case:.*loop" test-data/
# Check for other increment/decrement patterns
ast-grep --pattern 'if $_ < $_ goto $_'
# Look for any TODO comments about missing test cases
rg -i "todo.*loop" .
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Actionable comments posted: 2
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📒 Files selected for processing (1)
test-data/loop.yaml(1 hunks)
🧰 Additional context used
📓 Learnings (1)
test-data/loop.yaml (2)
Learnt from: Alan-Jowett
PR: vbpf/ebpf-verifier#745
File: test-data/loop.yaml:405-422
Timestamp: 2024-11-01T18:32:05.221Z
Learning: In `test-data/loop.yaml`, when test cases are focused on loop count, adding variations for negative initial values is unnecessary if they do not contribute to the analysis of loop count.
Learnt from: Alan-Jowett
PR: vbpf/ebpf-verifier#745
File: test-data/loop.yaml:377-398
Timestamp: 2024-10-25T19:31:59.214Z
Learning: In `test-data/loop.yaml`, for the test case **"very large loop > 100K iterations"**, additional post conditions like `r0.svalue>0` and `r0.uvalue>0` are not required.
| test-case: Count up loop | ||
| options: ["termination"] | ||
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| pre: [] | ||
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| code: | ||
| <start>: | | ||
| r0 = 0 | ||
| r1 = 0 | ||
| <loop>: | | ||
| r1 += 1 | ||
| if r1 < 10 goto <loop> | ||
| exit | ||
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| post: | ||
| - r0.svalue=0 | ||
| - r0.type=number | ||
| - r0.uvalue=0 | ||
| - r1.svalue=10 | ||
| - r1.type=number | ||
| - r1.uvalue=10 | ||
| - r1.svalue=r1.uvalue | ||
| - pc[2]=10 | ||
| - pc[2]=r1.svalue | ||
| - pc[2]=r1.uvalue | ||
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| messages: [] |
There was a problem hiding this comment.
🧹 Nitpick (assertive)
Add context about test case's relationship to issue #785.
The test case correctly implements and verifies a counting up loop. Consider adding a comment explaining how this test case relates to issue #785, particularly how it demonstrates the verifier's different behavior with incrementing vs decrementing loops.
test-case: Count up loop
options: ["termination"]
+# Complementary test to the count down loop case in issue #785.
+# This demonstrates that the verifier correctly handles incrementing loops,
+# in contrast to its incorrect behavior with decrementing loops.📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| test-case: Count up loop | |
| options: ["termination"] | |
| pre: [] | |
| code: | |
| <start>: | | |
| r0 = 0 | |
| r1 = 0 | |
| <loop>: | | |
| r1 += 1 | |
| if r1 < 10 goto <loop> | |
| exit | |
| post: | |
| - r0.svalue=0 | |
| - r0.type=number | |
| - r0.uvalue=0 | |
| - r1.svalue=10 | |
| - r1.type=number | |
| - r1.uvalue=10 | |
| - r1.svalue=r1.uvalue | |
| - pc[2]=10 | |
| - pc[2]=r1.svalue | |
| - pc[2]=r1.uvalue | |
| messages: [] | |
| test-case: Count up loop | |
| options: ["termination"] | |
| # Complementary test to the count down loop case in issue #785. | |
| # This demonstrates that the verifier correctly handles incrementing loops, | |
| # in contrast to its incorrect behavior with decrementing loops. | |
| pre: [] | |
| code: | |
| <start>: | | |
| r0 = 0 | |
| r1 = 0 | |
| <loop>: | | |
| r1 += 1 | |
| if r1 < 10 goto <loop> | |
| exit | |
| post: | |
| - r0.svalue=0 | |
| - r0.type=number | |
| - r0.uvalue=0 | |
| - r1.svalue=10 | |
| - r1.type=number | |
| - r1.uvalue=10 | |
| - r1.svalue=r1.uvalue | |
| - pc[2]=10 | |
| - pc[2]=r1.svalue | |
| - pc[2]=r1.uvalue | |
| messages: [] |
| # Issue: https://github.com/vbpf/ebpf-verifier/issues/785 | ||
| # The verifier incorrectly assumes that the loop is infinite. | ||
| test-case: Count down loop - incorrectly passes | ||
| options: ["termination"] | ||
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| pre: [] | ||
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| code: | ||
| <start>: | | ||
| r0 = 0 | ||
| r1 = 10 | ||
| <loop>: | | ||
| r1 -= 1 | ||
| if r1 > 1 goto <loop> | ||
| exit | ||
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| post: | ||
| - pc[2]=[1, +oo] | ||
| - r0.svalue=0 | ||
| - r0.type=number | ||
| - r0.uvalue=0 | ||
| - r1.svalue=[0, 1] | ||
| - r1.type=number | ||
| - r1.uvalue=[0, 1] | ||
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| messages: | ||
| - "2: Loop counter is too large (pc[2] < 100000)" | ||
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There was a problem hiding this comment.
🧹 Nitpick (assertive)
Enhance test documentation with more details about the verifier's behavior.
The test case correctly demonstrates the issue where the verifier incorrectly assumes an infinite loop. Consider adding more context in the comments about:
- Why the verifier incorrectly assumes this is an infinite loop
- What aspect of the decrementing counter confuses the verifier
- Expected vs actual behavior of the verifier
# Issue: https://github.com/vbpf/ebpf-verifier/issues/785
-# The verifier incorrectly assumes that the loop is infinite.
+# The verifier incorrectly assumes that the loop is infinite despite:
+# - Loop having a clear termination condition (r1 > 1)
+# - r1 being decremented from 10 to 1, which should terminate after 9 iterations
+# - No possibility of integer overflow that could cause infinite looping📝 Committable suggestion
‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.
| # Issue: https://github.com/vbpf/ebpf-verifier/issues/785 | |
| # The verifier incorrectly assumes that the loop is infinite. | |
| test-case: Count down loop - incorrectly passes | |
| options: ["termination"] | |
| pre: [] | |
| code: | |
| <start>: | | |
| r0 = 0 | |
| r1 = 10 | |
| <loop>: | | |
| r1 -= 1 | |
| if r1 > 1 goto <loop> | |
| exit | |
| post: | |
| - pc[2]=[1, +oo] | |
| - r0.svalue=0 | |
| - r0.type=number | |
| - r0.uvalue=0 | |
| - r1.svalue=[0, 1] | |
| - r1.type=number | |
| - r1.uvalue=[0, 1] | |
| messages: | |
| - "2: Loop counter is too large (pc[2] < 100000)" | |
| # Issue: https://github.com/vbpf/ebpf-verifier/issues/785 | |
| # The verifier incorrectly assumes that the loop is infinite despite: | |
| # - Loop having a clear termination condition (r1 > 1) | |
| # - r1 being decremented from 10 to 1, which should terminate after 9 iterations | |
| # - No possibility of integer overflow that could cause infinite looping | |
| test-case: Count down loop - incorrectly passes | |
| options: ["termination"] | |
| pre: [] | |
| code: | |
| <start>: | | |
| r0 = 0 | |
| r1 = 10 | |
| <loop>: | | |
| r1 -= 1 | |
| if r1 > 1 goto <loop> | |
| exit | |
| post: | |
| - pc[2]=[1, +oo] | |
| - r0.svalue=0 | |
| - r0.type=number | |
| - r0.uvalue=0 | |
| - r1.svalue=[0, 1] | |
| - r1.type=number | |
| - r1.uvalue=[0, 1] | |
| messages: | |
| - "2: Loop counter is too large (pc[2] < 100000)" |
This pull request adds new test cases to the
test-data/loop.yamlfile, which help in identifying issues related to loop verification in the eBPF verifier. The most important changes include adding test cases for a countdown loop that incorrectly passes and a count-up loop.New test cases added:
test-case: Count down loop - incorrectly passes: This test case highlights an issue where the verifier incorrectly assumes that the loop is infinite.test-case: Count up loop: This test case verifies the correct behavior of a loop that counts up to 10.Summary by CodeRabbit