From 2efa206862c05b3aaf9b2e017543bb320da883cf Mon Sep 17 00:00:00 2001
From: Emily Matheys <emilymatt96@gmail.com>
Date: Tue, 24 Feb 2026 16:37:54 +0200
Subject: [PATCH] fix: alloc(0) call is UB

---
 src/lib.rs | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 5a3051ac..f449fb42 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1051,6 +1051,15 @@ impl AlignedBuf {
     /// Creates a new buffer that is  aligned with the simd register size
     #[must_use]
     pub fn with_capacity(capacity: usize) -> Self {
+        if capacity == 0 {
+            let layout = Layout::from_size_align(0, SIMDJSON_PADDING).unwrap();
+            return Self {
+                layout,
+                capacity: 0,
+                len: 0,
+                inner: NonNull::dangling(),
+            };
+        }
         let Ok(layout) = Layout::from_size_align(capacity, SIMDJSON_PADDING) else {
             Self::capacity_overflow()
         };
@@ -1092,8 +1101,10 @@ impl AlignedBuf {
 }
 impl Drop for AlignedBuf {
     fn drop(&mut self) {
-        unsafe {
-            dealloc(self.inner.as_ptr(), self.layout);
+        if self.capacity > 0 {
+            unsafe {
+                dealloc(self.inner.as_ptr(), self.layout);
+            }
         }
     }
 }