Audit for write_bytes
#1102
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Audit for write_bytes
#1102
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danielsn
approved these changes
Apr 25, 2022
| align, | ||
| PropertyClass::DefaultAssertion, | ||
| "`dst` is properly aligned", | ||
| loc.clone(), |
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No need to clone locations
| ); | ||
| let layout = self.layout_of(ty); | ||
| let sz = Expr::int_constant(layout.size.bytes(), Type::size_t()); | ||
| let memset_call = BuiltinFn::Memset.call(vec![dst, val, count.mul(sz)], loc); |
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We have overflow checking on, right? So we'll see if this overflows?
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I checked it but we were not detecting overflows here. Updated to include an explicit overflow check for this computation. Added another test to check overflows.
| @@ -1156,4 +1149,34 @@ impl<'tcx> GotocCtx<'tcx> { | |||
| let expr = dst.dereference().assign(src, loc.clone()); | |||
| Stmt::block(vec![align_check, expr], loc) | |||
| } | |||
|
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| /// Sets `count * size_of::<T>()` bytes of memory starting at `dst` to `val` | |||
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Like the callout to the documentation
danielsn
approved these changes
Apr 26, 2022
Comment on lines
+1182
to
+1191
| // Check that computing `bytes` would not overflow | ||
| let layout = self.layout_of(ty); | ||
| let size = Expr::int_constant(layout.size.bytes(), Type::size_t()); | ||
| let bytes = count.mul_overflow(size); | ||
| let overflow_check = self.codegen_assert( | ||
| bytes.overflowed.not(), | ||
| PropertyClass::ArithmeticOverflow, | ||
| format!("{}: attempt to compute `bytes` which would overflow", intrinsic).as_str(), | ||
| loc, | ||
| ); |
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Not for this PR, but we've done this check > 1 times, which means a helper fn might be good
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Description of changes:
Moves and updates the
write_bytesintrinsic implementation with an alignment check that it was missing. Adds 3 tests cases (2 of them inexpected).Resolved issues:
Part of #727
Call-outs:
Testing:
How is this change tested? Adds 3 tests.
Is this a refactor change? No.
Checklist
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.