From bd555a0b3ecd3e2279f956bd01b777aa5b269134 Mon Sep 17 00:00:00 2001
From: Jishnu Bhattacharya <jishnub.github@gmail.com>
Date: Wed, 19 Mar 2025 17:34:42 +0530
Subject: [PATCH] Avoid accessing unset indices in symmetric copyto!

---
 src/symmetric.jl  |  4 ++--
 test/symmetric.jl | 15 +++++++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/symmetric.jl b/src/symmetric.jl
index 6c06dec1..85d8aa98 100644
--- a/src/symmetric.jl
+++ b/src/symmetric.jl
@@ -352,7 +352,7 @@ function copyto!(dest::Symmetric, src::Symmetric)
     elseif src.uplo == dest.uplo
         copytrito!(dest.data, src.data, src.uplo)
     else
-        transpose!(dest.data, Base.unalias(dest.data, src.data))
+        copytrito!(dest.data, transpose(Base.unalias(dest.data, src.data)), dest.uplo)
     end
     return dest
 end
@@ -363,7 +363,7 @@ function copyto!(dest::Hermitian, src::Hermitian)
     elseif src.uplo == dest.uplo
         copytrito!(dest.data, src.data, src.uplo)
     else
-        adjoint!(dest.data, Base.unalias(dest.data, src.data))
+        copytrito!(dest.data, adjoint(Base.unalias(dest.data, src.data)), dest.uplo)
     end
     return dest
 end
diff --git a/test/symmetric.jl b/test/symmetric.jl
index 68f0ff47..f653f4b9 100644
--- a/test/symmetric.jl
+++ b/test/symmetric.jl
@@ -1163,4 +1163,19 @@ end
     end
 end
 
+@testset "copyto! with mismatched uplo" begin
+    for (S,tf) in ((Symmetric, transpose), (Hermitian, adjoint))
+        for (uplo1,uplo2) in [(:U,:L), (:L, :U)]
+            M = Matrix{Complex{BigFloat}}(undef, 2, 2)
+            M[1,1] = M[2,2] = 3
+            isupper = uplo1 == :U
+            M[1+!isupper, 1+isupper] = 4+3im
+            H1 = S(M, uplo1)
+            H2 = 2 * S(tf(M), uplo2)
+            copyto!(H2, H1)
+            @test H2 == H1
+        end
+    end
+end
+
 end # module TestSymmetric