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[v2,4/6] mm, arm64: untag user addresses in mm/gup.c

Message ID 24ab244adc196fda8536cf2efb59cc654e1c234b.1525356769.git.andreyknvl@google.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andrey Konovalov May 3, 2018, 2:15 p.m. UTC 
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.

Add untagging to gup.c functions that use user pointers for vma lookup.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 mm/gup.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox

Patch

diff --git a/mm/gup.c b/mm/gup.c
index 76af4cfeaf68..65a9566c96d3 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -647,6 +647,8 @@  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 +803,8 @@  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;