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

From: Andrey Konovalov <andreyknvl@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Mark Rutland <mark.rutland@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Andrey Konovalov <andreyknvl@google.com>,
	James Morse <james.morse@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Bart Van Assche <bart.vanassche@wdc.com>,
	Kate Stewart <kstewart@linuxfoundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>,
	Zi Yan <zi.yan@cs.rutgers.edu>,
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Kostya Serebryany <kcc@google.com>,
	Evgeniy Stepanov <eugenis@google.com>,
	Lee Smith <Lee.Smith@arm.com>,
	Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>
Subject: [PATCH 4/6] mm, arm64: untag user addresses in mm/gup.c
Date: Wed, 18 Apr 2018 20:53:13 +0200	[thread overview]
Message-ID: <0db34d04fa16be162336106e3b4a94f3dacc0af4.1524077494.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1524077494.git.andreyknvl@google.com>
In-Reply-To: <cover.1524077494.git.andreyknvl@google.com>

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@google.com>
---
 mm/gup.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/mm/gup.c b/mm/gup.c
index 76af4cfeaf68..fb375de7d40d 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);
@@ -1751,6 +1759,8 @@ 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;
@@ -1803,6 +1813,8 @@ 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;
-- 
2.17.0.484.g0c8726318c-goog
