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virtio: skip redundant memory check #4723

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Merged
merged 3 commits into from
Aug 13, 2024
Merged

virtio: skip redundant memory check #4723

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e09658a
virtio: skip redundant memory check
ihciah Aug 6, 2024
7634cac
Merge branch 'main' into skip-redundant-check
ShadowCurse Aug 12, 2024
dca8801
Merge branch 'main' into skip-redundant-check
roypat Aug 13, 2024
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8 changes: 6 additions & 2 deletions src/vmm/src/devices/virtio/queue.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -96,6 +96,9 @@ pub struct DescriptorChain<'a, M: GuestMemory = GuestMemoryMmap> {
}

impl<'a, M: GuestMemory> DescriptorChain<'a, M> {
/// Creates a new `DescriptorChain` from the given memory and descriptor table.
///
/// Note that the desc_table and queue_size are assumed to be validated by the caller.
fn checked_new(
mem: &'a M,
desc_table: GuestAddress,
Expand All @@ -106,8 +109,9 @@ impl<'a, M: GuestMemory> DescriptorChain<'a, M> {
return None;
}

let desc_head = mem.checked_offset(desc_table, (index as usize) * 16)?;
mem.checked_offset(desc_head, 16)?;
// There's no need for checking as we already validated the descriptor table and index
// bounds.
let desc_head = desc_table.unchecked_add(u64::from(index) * 16);

// These reads can't fail unless Guest memory is hopelessly broken.
let desc = match mem.read_obj::<Descriptor>(desc_head) {
Expand Down