firecracker-microvm/firecracker · error

caddr should be within the region

Error message

caddr should be within the region

What it means

Error "caddr should be within the region" thrown in firecracker-microvm/firecracker.

Source

Thrown at src/vmm/src/vstate/memory.rs:610

            slot_size,
            region_type: state.region_type,
            slot_from,
            plugged: Mutex::new(BitVec::from_iter(state.plugged.iter())),
        })
    }

    /// Check whether the given guest address range falls within plugged slots.
    pub(crate) fn check_range_plugged(
        &self,
        caddr: MemoryRegionAddress,
        len: usize,
    ) -> Result<(), GuestMemoryError> {
        // caddr is guaranteed to be within the region by the caller
        // (try_for_each_region_in_range validates this).
        let from = self
            .start_addr()
            .checked_add(caddr.raw_value())
            .expect("caddr should be within the region");
        if self
            .slots_intersecting_range(from, len)
            .any(|(_, plugged)| !plugged)
        {
            return Err(GuestMemoryError::HostAddressNotAvailable);
        }
        Ok(())
    }

    pub(crate) fn slot_cnt(&self) -> u32 {
        u32::try_from(u64_to_usize(self.len()) / self.slot_size).unwrap()
    }

    pub(crate) fn mem_slot(&self, slot: u32) -> GuestMemorySlot<'_> {
        assert!(slot >= self.slot_from && slot < self.slot_from + self.slot_cnt());

        let offset = ((slot - self.slot_from) as u64) * (self.slot_size as u64);

View on GitHub (pinned to 9384f395f5)

Solutions

1. Ensure the guest physical address being accessed lies within the memory region it is looked up in.
2. Validate addresses from the guest before translating them to host addresses.

When it happens

Trigger: Thrown at src/vmm/src/vstate/memory.rs:610 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of firecracker-microvm/firecracker@9384f395f5 (2026-08-19). Data as JSON: /api/errors/589b95a405346a5e. Report an issue: GitHub.