George, Brian, I also think my patch is icky. George's patch may be nicer.
Thanks, Takahiro Kawashima, MPI development team, Fujitsu > Takahiro, > > Nice catch. A nicer fix will be to check the type of the header, and copy the > header accordingly. Attached is a patch following this idea. > > Thanks, > george. > > > On Oct 18, 2012, at 03:06 , "Kawashima, Takahiro" > <t-kawash...@jp.fujitsu.com> wrote: > > > Hi Open MPI developers, > > > > I found another issue in Open MPI. > > > > In MCA_PML_OB1_RECV_FRAG_INIT macro in ompi/mca/pml/ob1/pml_ob1_recvfrag.h > > file, we copy a PML header from an arrived message to another buffer, > > as follows: > > > > frag->hdr = *(mca_pml_ob1_hdr_t*)hdr; > > > > On this copy, we cast hdr to mca_pml_ob1_hdr_t, which is a union > > of all actual header structs such as mca_pml_ob1_match_hdr_t. > > This means we copy the buffer of the size of the largest header > > even if the arrived message is smaller than it. This can cause > > SEGV if the arrived message is small and it is laid on the bottom > > of the page. Actually, my tofu BTL, the BTL component of Fujitsu > > MPI for K computer, suffered from this. > > > > The attached patch will be one of possible fixes for this issue. > > This fix assume that the arrived header has at least segs[0].seg_len > > bytes. This is always true for current Open MPI code because hdr > > equals to segs[0].seg_addr.pval. There may exist a smarter fix.
