aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/scsi/sg.c
diff options
context:
space:
mode:
authorTodd Poynor <toddpoynor@google.com>2017-08-15 22:41:08 -0700
committerMartin K. Petersen <martin.petersen@oracle.com>2017-08-24 22:29:09 -0400
commit6a8dadcca81fceff9976e8828cceb072873b7bd5 (patch)
tree6a9cb8566b1554f8aaafd81fabce9cfc20122490 /drivers/scsi/sg.c
parent8d26f491116feaa0b16de370b6a7ba40a40fa0b4 (diff)
scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE
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>
Diffstat (limited to 'drivers/scsi/sg.c')
-rw-r--r--drivers/scsi/sg.c12
1 files changed, 9 insertions, 3 deletions
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index bda438e1fb1d..f5705a95319f 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -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

Privacy Policy