scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE (6a8dadcc) · Commits · 戴 / test

Take f_mutex around mmap() processing to protect against races with the SG_SET_RESERVED_SIZE ioctl. Ensure the reserve buffer length remains consistent during the mapping operation, and set the "mmap called" flag to prevent further changes to the reserved buffer size as an atomic operation with the mapping. [mkp: fixed whitespace] Signed-off-by:

Todd Poynor <toddpoynor@google.com> Acked-by:

Douglas Gilbert <dgilbert@interlog.com> Signed-off-by:

Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/sg.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -1262,6 +1262,7 @@ sg_mmap(struct file filp, struct vm_area_struct vma)
		unsigned long req_sz, len, sa;
		Sg_scatter_hold *rsv_schp;
		int k, length;
		int ret = 0;

		if ((!filp) \|\| (!vma) \|\| (!(sfp = (Sg_fd *) filp->private_data)))
		return -ENXIO;
		@@ -1272,8 +1273,11 @@ sg_mmap(struct file filp, struct vm_area_struct vma)
		if (vma->vm_pgoff)
		return -EINVAL; /* want no offset */
		rsv_schp = &sfp->reserve;
		if (req_sz > rsv_schp->bufflen)
		return -ENOMEM; /* cannot map more than reserved buffer */
		mutex_lock(&sfp->f_mutex);
		if (req_sz > rsv_schp->bufflen) {
		ret = -ENOMEM; /* cannot map more than reserved buffer */
		goto out;
		}

		sa = vma->vm_start;
		length = 1 << (PAGE_SHIFT + rsv_schp->page_order);
		@@ -1287,7 +1291,9 @@ sg_mmap(struct file filp, struct vm_area_struct vma)
		vma->vm_flags \|= VM_IO \| VM_DONTEXPAND \| VM_DONTDUMP;
		vma->vm_private_data = sfp;
		vma->vm_ops = &sg_mmap_vm_ops;
		return 0;
		out:
		mutex_unlock(&sfp->f_mutex);
		return ret;
		}

		static void

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