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    Subject[PATCH 4.20 62/80] IB/hfi1: Remove overly conservative VM_EXEC flag check
    Date
    4.20-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Michael J. Ruhl <michael.j.ruhl@intel.com>

    commit 7709b0dc265f28695487712c45f02bbd1f98415d upstream.

    Applications that use the stack for execution purposes cause userspace PSM
    jobs to fail during mmap().

    Both Fortran (non-standard format parsing) and C (callback functions
    located in the stack) applications can be written such that stack
    execution is required. The linker notes this via the gnu_stack ELF flag.

    This causes READ_IMPLIES_EXEC to be set which forces all PROT_READ mmaps
    to have PROT_EXEC for the process.

    Checking for VM_EXEC bit and failing the request with EPERM is overly
    conservative and will break any PSM application using executable stacks.

    Cc: <stable@vger.kernel.org> #v4.14+
    Fixes: 12220267645c ("IB/hfi: Protect against writable mmap")
    Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
    Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
    Reviewed-by: Ira Weiny <ira.weiny@intel.com>
    Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
    Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
    Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/infiniband/hw/hfi1/file_ops.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/drivers/infiniband/hw/hfi1/file_ops.c
    +++ b/drivers/infiniband/hw/hfi1/file_ops.c
    @@ -488,7 +488,7 @@ static int hfi1_file_mmap(struct file *f
    vmf = 1;
    break;
    case STATUS:
    - if (flags & (unsigned long)(VM_WRITE | VM_EXEC)) {
    + if (flags & VM_WRITE) {
    ret = -EPERM;
    goto done;
    }

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