From 34d1d30611efed490886f5eef9944e95e4563fcf Mon Sep 17 00:00:00 2001
From: Tim Holy <tim.holy@gmail.com>
Date: Mon, 29 Feb 2016 06:09:45 -0600
Subject: [PATCH] Check stride on preallocated output for matmul (fixes #15286)

---
 base/linalg/matmul.jl |  6 +++---
 test/linalg/matmul.jl | 10 ++++++++++
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/base/linalg/matmul.jl b/base/linalg/matmul.jl
index ca97c342ffbc6..7f16a8af885b9 100644
--- a/base/linalg/matmul.jl
+++ b/base/linalg/matmul.jl
@@ -256,7 +256,7 @@ function syrk_wrapper!{T<:BlasFloat}(C::StridedMatrix{T}, tA::Char, A::StridedVe
         return matmul3x3!(C,tA,tAt,A,A)
     end
 
-    if stride(A, 1) == 1 && stride(A, 2) >= size(A, 1)
+    if stride(A, 1) == stride(C, 1) == 1 && stride(A, 2) >= size(A, 1) && stride(C, 2) >= size(C, 1)
         return copytri!(BLAS.syrk!('U', tA, one(T), A, zero(T), C), 'U')
     end
     return generic_matmatmul!(C, tA, tAt, A, A)
@@ -287,7 +287,7 @@ function herk_wrapper!{T<:BlasReal}(C::Union{StridedMatrix{T}, StridedMatrix{Com
     # Result array does not need to be initialized as long as beta==0
     #    C = Array(T, mA, mA)
 
-    if stride(A, 1) == 1 && stride(A, 2) >= size(A, 1)
+    if stride(A, 1) == stride(C, 1) == 1 && stride(A, 2) >= size(A, 1) && stride(C, 2) >= size(C, 1)
         return copytri!(BLAS.herk!('U', tA, one(T), A, zero(T), C), 'U', true)
     end
     return generic_matmatmul!(C,tA, tAt, A, A)
@@ -330,7 +330,7 @@ function gemm_wrapper!{T<:BlasFloat}(C::StridedVecOrMat{T}, tA::Char, tB::Char,
         return matmul3x3!(C,tA,tB,A,B)
     end
 
-    if stride(A, 1) == stride(B, 1) == 1 && stride(A, 2) >= size(A, 1) && stride(B, 2) >= size(B, 1)
+    if stride(A, 1) == stride(B, 1) == stride(C, 1) == 1 && stride(A, 2) >= size(A, 1) && stride(B, 2) >= size(B, 1) && stride(C, 2) >= size(C, 1)
         return BLAS.gemm!(tA, tB, one(T), A, B, zero(T), C)
     end
     generic_matmatmul!(C, tA, tB, A, B)
diff --git a/test/linalg/matmul.jl b/test/linalg/matmul.jl
index ea4b0f2847da8..e7d8dbe9e6dfd 100644
--- a/test/linalg/matmul.jl
+++ b/test/linalg/matmul.jl
@@ -109,6 +109,16 @@ Aref = Ai[1:2:end,1:2:end]
 Asub = sub(Ai, 1:2:5, 1:2:4)
 @test Ac_mul_B(Asub, Asub) == Ac_mul_B(Aref, Aref)
 @test A_mul_Bc(Asub, Asub) == A_mul_Bc(Aref, Aref)
+# issue #15286
+let C = zeros(8, 8), sC = sub(C, 1:2:8, 1:2:8), B = reshape(map(Float64,-9:10),5,4)
+    @test At_mul_B!(sC, A, A) == A'*A
+    @test At_mul_B!(sC, A, B) == A'*B
+end
+let Aim = A .- im, C = zeros(Complex128,8,8), sC = sub(C, 1:2:8, 1:2:8), B = reshape(map(Float64,-9:10),5,4) .+ im
+    @test Ac_mul_B!(sC, Aim, Aim) == Aim'*Aim
+    @test Ac_mul_B!(sC, Aim, B) == Aim'*B
+end
+
 
 # syrk & herk
 A = reshape(1:1503, 501, 3).-750.0