Commit b06e1abf authored by Todd Poynor's avatar Todd Poynor Committed by Greg Kroah-Hartman

scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE

commit 6a8dadcc upstream.

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: default avatarTodd Poynor <toddpoynor@google.com>
Acked-by: default avatarDouglas Gilbert <dgilbert@interlog.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 5b9c6a54
......@@ -1244,6 +1244,7 @@ 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;
......@@ -1254,8 +1255,11 @@ 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);
......@@ -1269,7 +1273,9 @@ 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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