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authorTodd Poynor <toddpoynor@google.com>2017-08-15 22:41:08 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-09-13 14:09:45 -0700
commit0d7592a03b8abd032afa19aed99ab89dec7f394a (patch)
tree9497a84492f1815b6e9de66388ec9f514d536784
parent9a4cabf3bf8b0ac0993b9c45a37def6ec2d60da6 (diff)
downloadlinux-linaro-stable-0d7592a03b8abd032afa19aed99ab89dec7f394a.tar.gz
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 8a9e139e2853..fc1d9d33873f 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1254,6 +1254,7 @@ 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;
@@ -1264,8 +1265,11 @@ 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);
@@ -1279,7 +1283,9 @@ 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