From 142deef717bad843fc04c5afb925bfd9e7dc4305 Mon Sep 17 00:00:00 2001
From: Alex Gaynor <alex.gaynor@gmail.com>
Date: Sun, 21 Jul 2024 08:44:02 -0400
Subject: [PATCH] Fixed invariant violation in `MemBio::get_buf` with empty
 results

Pointer arguments to `slice::from_raw_parts` are required to be non-null. (See https://davidben.net/2024/01/15/empty-slices.html for details.)
---
 openssl/src/bio.rs | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/openssl/src/bio.rs b/openssl/src/bio.rs
index 96a63d19c4..1595f89f1b 100644
--- a/openssl/src/bio.rs
+++ b/openssl/src/bio.rs
@@ -63,7 +63,11 @@ impl MemBio {
         unsafe {
             let mut ptr = ptr::null_mut();
             let len = ffi::BIO_get_mem_data(self.0, &mut ptr);
-            slice::from_raw_parts(ptr as *const _ as *const _, len as usize)
+            if len == 0 {
+                &[]
+            } else {
+                slice::from_raw_parts(ptr as *const _ as *const _, len as usize)
+            }
         }
     }
 
@@ -83,3 +87,14 @@ cfg_if! {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::MemBio;
+
+    #[test]
+    fn test_mem_bio_get_buf_empty() {
+        let b = MemBio::new().unwrap();
+        assert_eq!(b.get_buf(), &[]);
+    }
+}