[v4,4/7] mm, arm64: untag user addresses in mm/gup.c
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Message ID 1203c510e5c34e97e5940688df075d69429e94de.1529507994.git.andreyknvl@google.com
State New
Headers show

Commit Message

Andrey Konovalov June 20, 2018, 3:24 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(+)

Patch
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diff --git a/mm/gup.c b/mm/gup.c
index b70d7ba7cc13..5bb351c91989 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -666,6 +666,8 @@  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));
 
 	/*
@@ -820,6 +822,8 @@  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;