diff options
| -rw-r--r-- | library/std/src/sys/sgx/abi/mem.rs | 42 |
1 files changed, 34 insertions, 8 deletions
diff --git a/library/std/src/sys/sgx/abi/mem.rs b/library/std/src/sys/sgx/abi/mem.rs index da899773dbb..3753fdd3536 100644 --- a/library/std/src/sys/sgx/abi/mem.rs +++ b/library/std/src/sys/sgx/abi/mem.rs @@ -47,20 +47,46 @@ pub fn image_base() -> u64 { /// Returns `true` if the specified memory range is in the enclave. /// -/// `p + len` must not overflow. +/// For safety, this function also checks whether the range given overflows, +/// returning `false` if so. #[unstable(feature = "sgx_platform", issue = "56975")] pub fn is_enclave_range(p: *const u8, len: usize) -> bool { - let start = p as u64; - let end = start + (len as u64); - start >= image_base() && end <= image_base() + (unsafe { ENCLAVE_SIZE } as u64) // unsafe ok: link-time constant + let start = p as usize; + + // Subtract one from `len` when calculating `end` in case `p + len` is + // exactly at the end of addressable memory (`p + len` would overflow, but + // the range is still valid). + let end = if len == 0 { + start + } else if let Some(end) = start.checked_add(len - 1) { + end + } else { + return false; + }; + + let base = image_base() as usize; + start >= base && end <= base + (unsafe { ENCLAVE_SIZE } - 1) // unsafe ok: link-time constant } /// Returns `true` if the specified memory range is in userspace. /// -/// `p + len` must not overflow. +/// For safety, this function also checks whether the range given overflows, +/// returning `false` if so. #[unstable(feature = "sgx_platform", issue = "56975")] pub fn is_user_range(p: *const u8, len: usize) -> bool { - let start = p as u64; - let end = start + (len as u64); - end <= image_base() || start >= image_base() + (unsafe { ENCLAVE_SIZE } as u64) // unsafe ok: link-time constant + let start = p as usize; + + // Subtract one from `len` when calculating `end` in case `p + len` is + // exactly at the end of addressable memory (`p + len` would overflow, but + // the range is still valid). + let end = if len == 0 { + start + } else if let Some(end) = start.checked_add(len - 1) { + end + } else { + return false; + }; + + let base = image_base() as usize; + end < base || start > base + (unsafe { ENCLAVE_SIZE } - 1) // unsafe ok: link-time constant } |