mm/gup.c provides a kernel interface that accepts user addresses and
manipulates user pages directly (for example get_user_pages, that is used
by the futex syscall). Here we also need to handle the case of tagged user
pointers.
Untag addresses passed to this interface.
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
mm/gup.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/mm/gup.c b/mm/gup.c
index 6afae32571ca..9c4afcf50dfa 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -386,6 +386,8 @@ struct page *follow_page_mask(struct vm_area_struct *vma,
struct page *page;
struct mm_struct *mm = vma->vm_mm;
+ address = untagged_addr(address);
+
*page_mask = 0;
/* make this handle hugepd */
@@ -647,6 +649,8 @@ static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
if (!nr_pages)
return 0;
+ start = untagged_addr(start);
+
VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
/*
@@ -801,6 +805,8 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
struct vm_area_struct *vma;
int ret, major = 0;
+ address = untagged_addr(address);
+
if (unlocked)
fault_flags |= FAULT_FLAG_ALLOW_RETRY;
@@ -854,6 +860,8 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk,
long ret, pages_done;
bool lock_dropped;
+ start = untagged_addr(start);
+
if (locked) {
/* if VM_FAULT_RETRY can be returned, vmas become invalid */
BUG_ON(vmas);
@@ -1749,6 +1757,8 @@ int __get_user_pages_fast(unsigned long start, int nr_pages, int write,
unsigned long flags;
int nr = 0;
+ start = untagged_addr(start);
+
start &= PAGE_MASK;
addr = start;
len = (unsigned long) nr_pages << PAGE_SHIFT;
@@ -1801,6 +1811,8 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
unsigned long addr, len, end;
int nr = 0, ret = 0;
+ start = untagged_addr(start);
+
start &= PAGE_MASK;
addr = start;
len = (unsigned long) nr_pages << PAGE_SHIFT;
--
2.17.0.rc0.231.g781580f067-goog
--
To unsubscribe from this list: send the line "unsubscribe linux-doc" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
