4.8-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dan Williams <dan.j.williams@xxxxxxxxx>
commit 4cb19355ea19995941ccaad115dbfac6b75215ca upstream.
The device-dax implementation originally tried to be tricky and allow
private read-only mappings, but in the process allowed writable
MAP_PRIVATE + MAP_NORESERVE mappings. For simplicity and predictability
just fail all private mapping attempts since device-dax memory is
statically allocated and will never support overcommit.
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap")
Reported-by: Pawel Lebioda <pawel.lebioda@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/dax/dax.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -323,8 +323,8 @@ static int check_vma(struct dax_dev *dax
if (!dax_dev->alive)
return -ENXIO;
- /* prevent private / writable mappings from being established */
- if ((vma->vm_flags & (VM_NORESERVE|VM_SHARED|VM_WRITE)) == VM_WRITE) {
+ /* prevent private mappings from being established */
+ if ((vma->vm_flags & VM_SHARED) != VM_SHARED) {
dev_info(dev, "%s: %s: fail, attempted private mapping\n",
current->comm, func);
return -EINVAL;
--
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