Home Home > GIT Browse
summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorTodd Poynor <toddpoynor@google.com>2017-08-15 22:41:08 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-09 17:39:42 +0200
commitb06e1abf1ff26046f0f3369b7abe8a221dadf26b (patch)
tree4c55d8badb58e8c1f649f4c4129a87a0c869cdfa
parent5b9c6a54c629e38271acf833f75154f2f8333365 (diff)
scsi: sg: protect against races between mmap() and SG_SET_RESERVED_SIZE
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>
-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 fed37aabf828..0506a776cc10 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -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