vtpm: add safety comments and fix small issues #574
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CC @cclaudio |
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CI is failing https://github.com/coconut-svsm/svsm/actions/runs/12428229021/job/34699433885?pr=574#step:7:1353 with: @joergroedel I'm not sure if it's related to this PR. |
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It looks like for some reason now the CI container doesn't have |
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Thanks, waiting a bit more for @cclaudio to approve. |
For some reason my inbox message filters did not pick this one, sorry about that. |
00xc
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| // SAFETY: vaddr is just mapped, and its size is PAGE_SIZE | ||
| let buffer = unsafe { from_raw_parts_mut(vaddr.as_mut_ptr::<u8>(), PAGE_SIZE) }; |
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Is this truly safe though? Isn't this a shared buffer? Creating a mutable reference to it is unsound if the contents can be modified by the guest.
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The guest should not touch it while issuing the SVSM call, which IIUC is also sync. @cclaudio can you confirm this?
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`Layout::from_size_align(size, align)` can return an error if following conditions are not met: - align must not be zero, - align must be a power of two, - size, when rounded up to the nearest multiple of align, must not overflow isize (i.e., the rounded value must be less than or equal to isize::MAX). Conditions on `align` are always met, but the size is specified by the caller, so it can fail. Let's propagate the error instead of panic. Signed-off-by: Stefano Garzarella <[email protected]>
The current implementation lacks some requirements defined by
POSIX documentation of `void *realloc(void *ptr, size_t size);`:
- If ptr is a null pointer, realloc() shall be equivalent to malloc()
for the specified size.
- If the size of the space requested is zero, the behavior shall be
implementation-defined.
In this case we are following Linux implementation, from malloc(3)
man page:
- If size is equal to zero, and ptr is not NULL, then the call is
equivalent to free(ptr).
[1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/realloc.html
Signed-off-by: Stefano Garzarella <[email protected]>
Add SAFETY comments around calls to GlobalAlloc and checks as required by the documentation[1], especially on non-zero size and pointer validity. [1] https://doc.rust-lang.org/alloc/alloc/trait.GlobalAlloc.html Signed-off-by: Stefano Garzarella <[email protected]>
Add SAFETY comments around FFI calls and some checks for return values. Signed-off-by: Stefano Garzarella <[email protected]>
Add SAFETY comment around `from_raw_parts_mut()` call. Signed-off-by: Stefano Garzarella <[email protected]>
In several places we use `if let Ok(foo) = func() {` creating large
indented blocks, let's replace with `let Ok(foo) = func() else {` by
immediately returning a null pointer and reducing the indentation
to make the code more readable.
Suggested-by: Carlos López <[email protected]>
Signed-off-by: Stefano Garzarella <[email protected]>
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This is part of the effort for #228 to enable
undocumented_unsafe_blocksclippy lint.