iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

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

Browse Source 
commit 6a8dadcca81fceff9976e8828cceb072873b7bd5 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: Todd Poynor <toddpoynor@google.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Todd Poynor 2017-08-15 22:41:08 -07:00 committed by Greg Kroah-Hartman
parent 5b9c6a54c6
commit b06e1abf1f
1 changed files with 9 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
drivers/scsi/sg.c
View File

@ -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