3.16.85-rc1 review patch. If anyone has any objections, please let me know.
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From: Todd Poynor toddpoynor@google.com
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 Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/scsi/sg.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
--- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -1310,6 +1310,7 @@ sg_mmap(struct file *filp, struct vm_are 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; @@ -1319,8 +1320,11 @@ sg_mmap(struct file *filp, struct vm_are 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); @@ -1334,7 +1338,9 @@ sg_mmap(struct file *filp, struct vm_are 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