rust: bssl-tls: Check with the right buffer size limit for Rust FFI

Signed-off-by: Xiangfei Ding <xfding@google.com>
Change-Id: I4b7974f93d1a87a15a176f838488da786a6a6964
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/92507
Reviewed-by: Adam Langley <agl@google.com>

rust/bssl-tls/src/ffi.rs

diff --git a/rust/bssl-tls/src/ffi.rs b/rust/bssl-tls/src/ffi.rs
index 57be38d..ae06821 100644
--- a/rust/bssl-tls/src/ffi.rs
+++ b/rust/bssl-tls/src/ffi.rs
@@ -47,7 +47,7 @@
     if len == 0 || input.is_null() {
         return Some(&[]);
     }
-    if !input.is_aligned() || len.checked_mul(size_of::<T>())? >= isize::MAX as usize {
+    if !input.is_aligned() || len.checked_mul(size_of::<T>())? > isize::MAX as usize {
         return None;
     }
     unsafe {
@@ -71,7 +71,7 @@
     if capacity == 0 || out.is_null() || !out.is_aligned() {
         return Some(&mut []);
     }
-    if capacity.checked_mul(size_of::<T>())? >= isize::MAX as usize {
+    if capacity.checked_mul(size_of::<T>())? > isize::MAX as usize {
         return None;
     }
     unsafe {