linux-kernel - [PATCH] binder: fix sparse issue in binder_alloc

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Date:   Wed, 13 Feb 2019 11:48:53 -0800
From:   Todd Kjos <tkjos@...roid.com>
To:     tkjos@...gle.com, gregkh@...uxfoundation.org, arve@...roid.com,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        maco@...gle.com
Cc:     joel@...lfernandes.org, kernel-team@...roid.com,
        kbuild test robot <lkp@...el.com>
Subject: [PATCH] binder: fix sparse issue in binder_alloc_selftest.c

Fixes sparse issues reported by the kbuild test robot running
on https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
char-misc-testing: bde4a19fc04f5 ("binder: use userspace pointer as base
of buffer space")

Error output (drivers/android/binder_alloc_selftest.c):
sparse: warning: incorrect type in assignment (different address spaces)
sparse:    expected void *page_addr
sparse:    got void [noderef] <asn:1> *user_data
sparse: error: subtraction of different types can't work

Fixed by adding necessary "__user" tags.

Reported-by: kbuild test robot <lkp@...el.com>
Signed-off-by: Todd Kjos <tkjos@...gle.com>
---
 drivers/android/binder_alloc_selftest.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/android/binder_alloc_selftest.c b/drivers/android/binder_alloc_selftest.c
index f0f4d7d026351..b72708918b06b 100644
--- a/drivers/android/binder_alloc_selftest.c
+++ b/drivers/android/binder_alloc_selftest.c
@@ -102,10 +102,11 @@ static bool check_buffer_pages_allocated(struct binder_alloc *alloc,
 					 struct binder_buffer *buffer,
 					 size_t size)
 {
-	void *page_addr, *end;
+	void __user *page_addr;
+	void __user *end;
 	int page_index;
 
-	end = (void *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
+	end = (void __user *)PAGE_ALIGN((uintptr_t)buffer->user_data + size);
 	page_addr = buffer->user_data;
 	for (; page_addr < end; page_addr += PAGE_SIZE) {
 		page_index = (page_addr - alloc->buffer) / PAGE_SIZE;
-- 
2.20.1.791.gb4d0f1c61a-goog