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RULE-11-3: Permit cast to pointer-to-void #317

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lcartey opened this issue Jun 28, 2023 · 3 comments · Fixed by #744
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RULE-11-3: Permit cast to pointer-to-void #317

lcartey opened this issue Jun 28, 2023 · 3 comments · Fixed by #744
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@lcartey
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Difficulty-Low A false positive or false negative report which is expected to take <1 day effort to address false positive/false negative An issue related to observed false positives or false negatives. Impact-High user-report Issue reported by an end user of CodeQL Coding Standards

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@lcartey
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lcartey commented Jun 28, 2023 •
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Affected rules

  • RULE-11-3
  • RULE-11-4
  • RULE-11-5
  • RULE-11-7

Description

The rule states that "a cast shall not be performed between a pointer to object type and a pointer to a different object type". However, void isn't a different object type. Rule 11.5 handles pointer-to-void, prohibiting casting from pointer-to-void, but permitting casting to pointer-to-void.

Update: this has been determined to be a problem specifically with const void * and other specified void pointers.

Example

uint32_t *p32;
void *p;
p = p32; // Compliant
@lcartey lcartey added the false positive/false negative An issue related to observed false positives or false negatives. label Jun 28, 2023
@lcartey lcartey added Difficulty-Medium A false positive or false negative report which is expected to take 1-5 days effort to address Difficulty-Low A false positive or false negative report which is expected to take <1 day effort to address user-report Issue reported by an end user of CodeQL Coding Standards Impact-High and removed Difficulty-Medium A false positive or false negative report which is expected to take 1-5 days effort to address labels Nov 20, 2023
@lcartey lcartey self-assigned this Jan 14, 2024
@ravikprasad
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Can this be prioritized and incorporated in the current MISRA C 2023 work?

@lcartey lcartey moved this from Assigned to In Progress in Coding Standards Public Development Board Oct 11, 2024
@lcartey
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lcartey commented Oct 11, 2024

After further investigation, the problem with this query is that it doesn't exclude const void pointers - the determination of a whether a pointer is a pointer-to-object is confused by the presence of specifiers. This is not limited to RULE-11-3 - it also affects RULE-11-4, RULE-11-5 & RULE-11-7.

@lcartey lcartey moved this from In Progress to Ready for review in Coding Standards Public Development Board Oct 11, 2024
@lcartey lcartey mentioned this issue Oct 11, 2024
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@lcartey
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lcartey commented Oct 11, 2024

PR opened to address this issue:
#744

@github-project-automation github-project-automation bot moved this from Ready for review to Done in Coding Standards Public Development Board Oct 15, 2024
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@lcartey lcartey

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Difficulty-Low A false positive or false negative report which is expected to take <1 day effort to address false positive/false negative An issue related to observed false positives or false negatives. Impact-High user-report Issue reported by an end user of CodeQL Coding Standards
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RULE-11-*: Improve detection of const void pointers github/codeql-coding-standards
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@lcartey @ravikprasad