adding 0 size test

src/shims/unix/foreign_items.rs

@@ -316,7 +316,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                 // (MSVC explicitly does not support this.)
                 let [align, size] =
                     this.check_shim(abi, Abi::C { unwind: false }, link_name, args)?;
-                let mut align = this.read_target_usize(align)?;
+                let align = this.read_target_usize(align)?;
                 let size = this.read_target_usize(size)?;
 
                 // The size must be a power of the alignment.
@@ -334,12 +334,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                             let _ = this.set_last_error(this.eval_libc("EINVAL"));
                             this.write_null(dest)?;
                         } else {
-                            if align < this.pointer_size().bytes() {
-                                align = this.pointer_size().bytes();
+                            let mut align = Align::from_bytes(align).unwrap();
+                            let min_align = this.malloc_align(size);
+                            if align < min_align {
+                                align = min_align;
                             }
                             let ptr = this.allocate_ptr(
                                 Size::from_bytes(size),
-                                Align::from_bytes(align).unwrap(),
+                                align,
                                 MiriMemoryKind::C.into(),
                             )?;
                             this.write_pointer(ptr, dest)?;

tests/fail-dep/libc/aligned_alloc.rs

@@ -0,0 +1,14 @@
+//@ignore-target-windows: Windows does not support the standard C11 aligned_alloc.
+
+fn main() {
+    // libc doesn't have this function (https://github.com/rust-lang/libc/issues/3689),
+    // so we declare it ourselves.
+    extern "C" {
+        fn aligned_alloc(alignment: libc::size_t, size: libc::size_t) -> *mut libc::c_void;
+    }
+
+    unsafe {
+        aligned_alloc(2, 0); //~ERROR: memory leaked
+    }
+}
+

tests/fail-dep/libc/aligned_alloc.stderr

@@ -0,0 +1,15 @@
+error: memory leaked: ALLOC (C heap, size: 0, align: 2), allocated here:
+  --> $DIR/aligned_alloc.rs:LL:CC
+   |
+LL |         aligned_alloc(2, 0);
+   |         ^^^^^^^^^^^^^^^^^^^
+   |
+   = note: BACKTRACE:
+   = note: inside `main` at $DIR/aligned_alloc.rs:LL:CC
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+
+error: aborting due to 1 previous error
+