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Fix CodeQL reports on crunch and crnlib #60

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Fix CodeQL reports on crunch and crnlib #60

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illwieckz
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@illwieckz illwieckz commented Jul 6, 2024 •
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Fix CodeQL reports.

The following cpp/static-buffer-overflow critical error is dismissed as it is a false positive:

Potential buffer-overflow: 'm_buf' has size 2 but 'm_buf[3]' may be accessed here.

It is a false positive because the tool fails to understand that the value tested for the switch case is the array size itself.

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That doesn't work… :-/

@illwieckz illwieckz marked this pull request as draft July 6, 2024 03:08
@illwieckz illwieckz changed the title Attempt to silence false positive CodeQL cpp/static-buffer-overflow WIP: Attempt to silence false positive CodeQL cpp/static-buffer-overflow Jul 6, 2024
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slipher commented Jul 6, 2024

This analyzer has a diff-only mode, right? (The one where it comments on pull requests.) So there is really no need to restructure everything to please the computer.

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Yes, and one can dismiss some reports, but I would have preferred if the tool was happy without doing manual tricks in the tool UI as moving or copying the code or just restyling it would bring the false positive back. I was hoping a simple rewrite may help it to get it, it looks like not.

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It is also very likely that GitHub would report the false positive on every fork even if we dismiss it there.

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Well, there is no way to avoid that false positive report, I don't know how to report it to CodeQL but they definitely fail to take in account this is a template and they should not test array[N] with an index greater than N. In fact I actually expect the compiler to remove any alternative code, and then remove the code I may write to silence the CodeQL report.

@illwieckz illwieckz changed the title WIP: Attempt to silence false positive CodeQL cpp/static-buffer-overflow WIP: Attempt to fix CodeQL reports Jul 10, 2024
@illwieckz illwieckz force-pushed the illwieckz/codeql-fixes branch 2 times, most recently from 951d912 to ed5344a Compare July 10, 2024 22:03
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The commit fixing stb_image.h was also reported to:

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illwieckz commented Jul 10, 2024 •
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Interesting, something broke the tool!

@illwieckz illwieckz force-pushed the illwieckz/codeql-fixes branch 2 times, most recently from 52ac792 to 5abcc45 Compare July 10, 2024 22:55
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Interesting, something broke the tool!

Fixed.

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So there is nothing left reported by CodeQL, the false-positive template ones were dismissed, all the other ones were fixed.

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illwieckz commented Jul 10, 2024 •
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The choice of doing static_cast<double>(x) or (double)x was decided by what was doing the code living immediately before or after the change, to keep the wording consistent. When the wording is not consistent within a file, it means the file was already not consistant among its various parts, and I made sure the wording was consistent within each parts.

@illwieckz illwieckz changed the title WIP: Attempt to fix CodeQL reports Fix CodeQL reports Jul 10, 2024
@illwieckz illwieckz marked this pull request as ready for review July 10, 2024 23:16
@illwieckz illwieckz changed the title Fix CodeQL reports Fix CodeQL reports on crunch and crnlib Jul 10, 2024
@illwieckz illwieckz force-pushed the illwieckz/codeql-fixes branch 2 times, most recently from c4357a9 to 85c1749 Compare July 12, 2024 02:44
slipher
slipher reviewed Jul 14, 2024
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crunch/crunch.cpp
@@ -958,7 +958,7 @@ class crunch {
else {
console::info("CRN texture info:");

console::info("Width: %u, Height: %u, Levels: %u, Faces: %u\nBytes per block: %u, User0: 0x%08X, User1: 0x%08X, CRN Format: %u",
console::info("Width: %u, Height: %u, Levels: %u, Faces: %u\nBytes per block: %u, User0: 0x%08X, User1: 0x%08X, CRN Format: %l",
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This one doesn't quite fix the issue... apparently the crn_format enum, having both a -1 value and a 2^32 - 1 value, is a different size depending on the compiler. In MSVC it is 32 bits but in some others it must be 64. We could force it to be a specific type with the C++11 feature enum crn_format: uint32_t or whatever, instead of the old approach of trying to influence the type by adding fake values.

crnlib/crn_image_utils.cpp
@@ -570,9 +570,9 @@ bool resample_multithreaded(const image_u8& src, image_u8& dst, const resample_p
return false;

p.m_pSrc_pixels = src_samples.get_ptr();
p.m_src_pitch = src_width * resampler_comps * sizeof(float);
p.m_src_pitch = (size_t)src_width * (size_t)resampler_comps * sizeof(float);
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Crunch has a maximum image dimension of 4096 so we don't ever need to worry about super-sized memory allocations.

crnlib/crn_clusterizer.h
@@ -53,7 +53,7 @@ class clusterizer {
root.m_total_weight += weight;
root.m_vectors.push_back(i);

ttsum += v.dot(v) * weight;
ttsum += (double)v.dot(v) * (double)weight;
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Can we just disable float/double precision warnings please? It simply doesn't matter. This is a lossy image compression program.

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This is CodeQL static analysis report, not a compiler warning.

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I know that. It should be configurable.

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