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[v3,4/6] mm, arm64: untag user addresses in mm/gup.c

Message ID 858608ce6ace4ebd71c0318d3d536e9d1918b613.1527268727.git.andreyknvl@google.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andrey Konovalov May 25, 2018, 5:21 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 541904a7c60f..5d0e9715bab7 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -650,6 +650,8 @@  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));
 
 	/*
@@ -804,6 +806,8 @@  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;