Dear all, under certain circumstances a call to MATMUL for rank-2 times rank-1 would invoke a highly tuned rank-2 times rank-2 algorithm which could lead to invalid reads and writes. The solution is to check the rank of the second argument to matmul and fall back to a regular algorithm for rank-1. The invalid accesses did show up with valgrind. I have not been able to create a testcase that gives wrong results. Regtested on x86_64-pc-linux-gnu, and verified with valgrind. OK for master? As this affects all open branches down to 8, ok for backports? Thanks, Harald PR libfortran/99218 - matmul on temporary array accesses invalid memory Do not invoke tuned rank-2 times rank-2 matmul if rank(b) == 1. libgfortran/ChangeLog: PR libfortran/99218 * m4/matmul_internal.m4: Invoke tuned matmul only for rank(b)>1. * generated/matmul_c10.c: Regenerated. * generated/matmul_c16.c: Likewise. * generated/matmul_c4.c: Likewise. * generated/matmul_c8.c: Likewise. * generated/matmul_i1.c: Likewise. * generated/matmul_i16.c: Likewise. * generated/matmul_i2.c: Likewise. * generated/matmul_i4.c: Likewise. * generated/matmul_i8.c: Likewise. * generated/matmul_r10.c: Likewise. * generated/matmul_r16.c: Likewise. * generated/matmul_r4.c: Likewise. * generated/matmul_r8.c: Likewise. * generated/matmulavx128_c10.c: Likewise. * generated/matmulavx128_c16.c: Likewise. * generated/matmulavx128_c4.c: Likewise. * generated/matmulavx128_c8.c: Likewise. * generated/matmulavx128_i1.c: Likewise. * generated/matmulavx128_i16.c: Likewise. * generated/matmulavx128_i2.c: Likewise. * generated/matmulavx128_i4.c: Likewise. * generated/matmulavx128_i8.c: Likewise. * generated/matmulavx128_r10.c: Likewise. * generated/matmulavx128_r16.c: Likewise. * generated/matmulavx128_r4.c: Likewise. * generated/matmulavx128_r8.c: Likewise.