From mboxrd@z Thu Jan  1 00:00:00 1970
From: andreyknvl@google.com (Andrey Konovalov)
Date: Wed, 20 Jun 2018 17:24:23 +0200
Subject: [PATCH v4 4/7] mm, arm64: untag user addresses in mm/gup.c
In-Reply-To: <cover.1529507994.git.andreyknvl@google.com>
References: <cover.1529507994.git.andreyknvl@google.com>
Message-ID:
 <1203c510e5c34e97e5940688df075d69429e94de.1529507994.git.andreyknvl@google.com>
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Message-ID: <20180620152423.VTJEvkoODsQf5R1EFvR9_JeiJWkT0nh43-kACOicGLo@z>

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 at google.com>
---
 mm/gup.c | 4 ++++
 1 file changed, 4 insertions(+)

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;
 
-- 
2.18.0.rc1.244.gcf134e6275-goog

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