Commit ecc53f8a authored Jul 23, 2019 by Andrey Konovalov Committed by Jason Gunthorpe Jul 24, 2019

RDMA/mlx4: Untag user pointers in mlx4_get_umem_mr

This patch is a part of a series that extends kernel ABI to allow to pass
tagged user pointers (with the top byte set to something else other than
0x00) as syscall arguments.

mlx4_get_umem_mr() uses provided user pointers for vma lookups, which can
only by done with untagged pointers.

Untag user pointers in this function.

Link: https://lore.kernel.org/r/7969018013a67ddbbf784ac7afeea5a57b1e2bcb.1563904656.git.andreyknvl@google.com


Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

parent 795130b3

drivers/infiniband/hw/mlx4/mr.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -377,6 +377,7 @@ static struct ib_umem mlx4_get_umem_mr(struct ib_udata udata, u64 start,
		* again
		*/
		if (!ib_access_writable(access_flags)) {
		unsigned long untagged_start = untagged_addr(start);
		struct vm_area_struct *vma;

		down_read(&current->mm->mmap_sem);
		@@ -385,9 +386,9 @@ static struct ib_umem mlx4_get_umem_mr(struct ib_udata udata, u64 start,
		* cover the memory, but for now it requires a single vma to
		* entirely cover the MR to support RO mappings.
		*/
		vma = find_vma(current->mm, start);
		if (vma && vma->vm_end >= start + length &&
		vma->vm_start <= start) {
		vma = find_vma(current->mm, untagged_start);
		if (vma && vma->vm_end >= untagged_start + length &&
		vma->vm_start <= untagged_start) {
		if (vma->vm_flags & VM_WRITE)
		access_flags \|= IB_ACCESS_LOCAL_WRITE;
		} else {

Admin message