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From: Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH v2 5/6] lib, arm64: untag addrs passed to strncpy_from_user and strnlen_user
Date: Thu,  3 May 2018 16:15:43 +0200
Message-Id: <98e18e4ca8e40bb8e7ea8e622833ce9123207e1e.1525356769.git.andreyknvl@google.com>
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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>, Chintan Pandya <cpandya@codeaurora.org>

strncpy_from_user and strnlen_user accept user addresses as arguments, and
do not go through the same path as copy_from_user and others, so here we
need to handle the case of tagged user addresses separately.

Untag user pointers passed to these functions.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 lib/strncpy_from_user.c | 2 ++
 lib/strnlen_user.c      | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c
index b53e1b5d80f4..97467cd2bc59 100644
--- a/lib/strncpy_from_user.c
+++ b/lib/strncpy_from_user.c
@@ -106,6 +106,8 @@ long strncpy_from_user(char *dst, const char __user *src, long count)
 	if (unlikely(count <= 0))
 		return 0;
 
+	src = untagged_addr(src);
+
 	max_addr = user_addr_max();
 	src_addr = (unsigned long)src;
 	if (likely(src_addr < max_addr)) {
diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c
index 60d0bbda8f5e..8b5f56466e00 100644
--- a/lib/strnlen_user.c
+++ b/lib/strnlen_user.c
@@ -108,6 +108,8 @@ long strnlen_user(const char __user *str, long count)
 	if (unlikely(count <= 0))
 		return 0;
 
+	str = untagged_addr(str);
+
 	max_addr = user_addr_max();
 	src_addr = (unsigned long)str;
 	if (likely(src_addr < max_addr)) {
-- 
2.17.0.441.gb46fe60e1d-goog