From f9b36d7a8d26251975218d17c677200a1e71e750 Mon Sep 17 00:00:00 2001 From: Erin Date: Wed, 26 Jul 2023 02:28:14 +0200 Subject: [PATCH] Fixed few overflows --- hbvm/src/lib.rs | 52 +++++++++++++++++++++++++++++---------------- hbvm/src/mem/bmc.rs | 46 +++++++++++++++++++++++++++------------ 2 files changed, 67 insertions(+), 31 deletions(-) diff --git a/hbvm/src/lib.rs b/hbvm/src/lib.rs index c2c28a4..e9a01e3 100644 --- a/hbvm/src/lib.rs +++ b/hbvm/src/lib.rs @@ -230,27 +230,26 @@ impl<'a, PfHandler: HandlePageFault, const TIMER_QUOTIENT: usize> LD => { // Load. If loading more than register size, continue on adjecent registers let ParamBBDH(dst, base, off, count) = self.decode(); - ldst_bound_check(dst, count)?; - - let n: usize = match dst { + let n: u8 = match dst { 0 => 1, _ => 0, }; self.memory.load( - self.read_reg(base).cast::() + off + n as u64, - self.registers.as_mut_ptr().add(usize::from(dst) + n).cast(), - usize::from(count).saturating_sub(n), + self.ldst_addr_uber(dst, base, off, count, n)?, + self.registers + .as_mut_ptr() + .add(usize::from(dst) + usize::from(n)) + .cast(), + usize::from(count).saturating_sub(n.into()), &mut self.pfhandler, )?; } ST => { // Store. Same rules apply as to LD let ParamBBDH(dst, base, off, count) = self.decode(); - ldst_bound_check(dst, count)?; - self.memory.store( - self.read_reg(base).cast::() + off, + self.ldst_addr_uber(dst, base, off, count, 0)?, self.registers.as_ptr().add(usize::from(dst)).cast(), count.into(), &mut self.pfhandler, @@ -312,7 +311,8 @@ impl<'a, PfHandler: HandlePageFault, const TIMER_QUOTIENT: usize> // specified register and jump to reg + offset. let ParamBBD(save, reg, offset) = self.decode(); self.write_reg(save, self.pc as u64); - self.pc = (self.read_reg(reg).cast::() + offset) as usize; + self.pc = + (self.read_reg(reg).cast::().saturating_add(offset)) as usize; } // Conditional jumps, jump only to immediates JEQ => self.cond_jmp::(Ordering::Equal), @@ -443,15 +443,28 @@ impl<'a, PfHandler: HandlePageFault, const TIMER_QUOTIENT: usize> *self.registers.get_unchecked_mut(n as usize) = value.into(); } } -} -/// Load/Store target/source register range bound checking -#[inline] -fn ldst_bound_check(reg: u8, size: u16) -> Result<(), VmRunError> { - if usize::from(reg) * 8 + usize::from(size) > 2048 { - Err(VmRunError::RegOutOfBounds) - } else { - Ok(()) + /// Load / Store Address check-computation überfunction + #[inline] + unsafe fn ldst_addr_uber( + &self, + dst: u8, + base: u8, + offset: u64, + size: u16, + adder: u8, + ) -> Result { + let reg = dst.checked_add(adder).ok_or(VmRunError::RegOutOfBounds)?; + + if usize::from(reg) * 8 + usize::from(size) > 2048 { + Err(VmRunError::RegOutOfBounds) + } else { + self.read_reg(base) + .cast::() + .checked_add(offset) + .and_then(|x| x.checked_add(adder.into())) + .ok_or(VmRunError::AddrOutOfBounds) + } } } @@ -471,6 +484,9 @@ pub enum VmRunError { /// Register out-of-bounds access RegOutOfBounds, + /// Address out-of-bounds + AddrOutOfBounds, + /// Reached unreachable code Unreachable, } diff --git a/hbvm/src/mem/bmc.rs b/hbvm/src/mem/bmc.rs index b561b90..fd43d73 100644 --- a/hbvm/src/mem/bmc.rs +++ b/hbvm/src/mem/bmc.rs @@ -36,7 +36,7 @@ impl BlockCopier { } /// Copy one block - /// + /// /// # Safety /// - Same as for [`Memory::load`] and [`Memory::store`] pub unsafe fn poll( @@ -59,8 +59,16 @@ impl BlockCopier { return Poll::Ready(Err(e)); } - self.src += BUF_SIZE as u64; - self.dst += BUF_SIZE as u64; + match self.src.checked_add(BUF_SIZE as u64) { + Some(n) => self.src = n, + None => return Poll::Ready(Err(BlkCopyError::OutOfBounds)), + }; + + match self.dst.checked_add(BUF_SIZE as u64) { + Some(n) => self.dst = n, + None => return Poll::Ready(Err(BlkCopyError::OutOfBounds)), + }; + self.n_buffers -= 1; return if self.n_buffers + self.rem == 0 { @@ -109,7 +117,7 @@ unsafe fn act( |src, dst, count| core::ptr::copy(src, dst, count), traph, ) - .map_err(|addr| BlkCopyError { + .map_err(|addr| BlkCopyError::Access { access_reason: MemoryAccessReason::Load, addr, })?; @@ -125,7 +133,7 @@ unsafe fn act( |dst, src, count| core::ptr::copy(src, dst, count), traph, ) - .map_err(|addr| BlkCopyError { + .map_err(|addr| BlkCopyError::Access { access_reason: MemoryAccessReason::Store, addr, })?; @@ -135,18 +143,30 @@ unsafe fn act( /// Error occured when copying a block of memory #[derive(Clone, Copy, Debug, PartialEq, Eq)] -pub struct BlkCopyError { - /// Kind of access - access_reason: MemoryAccessReason, - /// VM Address - addr: u64, +pub enum BlkCopyError { + /// Memory access error + Access { + /// Kind of access + access_reason: MemoryAccessReason, + /// VM Address + addr: u64, + }, + /// Address out of bounds + OutOfBounds, } impl From for VmRunError { fn from(value: BlkCopyError) -> Self { - match value.access_reason { - MemoryAccessReason::Load => Self::LoadAccessEx(value.addr), - MemoryAccessReason::Store => Self::StoreAccessEx(value.addr), + match value { + BlkCopyError::Access { + access_reason: MemoryAccessReason::Load, + addr, + } => Self::LoadAccessEx(addr), + BlkCopyError::Access { + access_reason: MemoryAccessReason::Store, + addr, + } => Self::StoreAccessEx(addr), + BlkCopyError::OutOfBounds => Self::AddrOutOfBounds, } } }